Spending on teaching staff makes up the largest share of education expenditure. The level of teachers’ salary costs per student depends on four factors: students’ instruction hours, teachers’ teaching hours and average class sizes (which together determine the number of teachers needed), and teachers’ salaries.
The two main factors influencing annual teachers’ salary costs are teachers’ salaries and class sizes. Between 2015 and 2023, teachers’ salaries in primary education increased in three-quarters of OECD countries with available data, and by 7% in real terms on average. Over the same period, average class sizes decreased in about two-thirds of countries. Both trends contribute to a higher salary cost per student, as rising salaries increase overall expenditure and smaller class sizes require more teachers for the same number of students.
Higher education levels tend to incur a higher teachers’ salary cost per student. On average across OECD countries, salary costs rise from USD 3 993 per student in primary education to USD 4 444 in lower secondary education. This is mostly due to a combination of higher teachers’ salaries and instruction time, and shorter teaching hours.
Education at a Glance 2025
Context
Governments have become increasingly interested in the relationship between the amount of resources devoted to education and student learning outcomes. They seek to provide more and better education for their populations, while ensuring that public funding is used efficiently, particularly when public budgets are tight. Teachers’ compensation usually accounts for the largest share of expenditure on education and thus of expenditure per student. The salary cost of teachers per student, as calculated in this chapter, is a function of students’ instruction time, the number of hours that a single teacher teaches a full class, actual teachers’ salaries and average class sizes (see Methodology section below and Box D4.1).
This chapter examines the choices countries make when investing their resources in primary and lower secondary education and explores how different policy choices related to these factors affect overall teachers’ salary costs. The salary cost of teachers per student can be affected by other variables not directly assessed in this indicator, such as demographic changes. In countries where enrolment has been declining in recent years, class sizes would also be expected to shrink (assuming all other factors remain constant). However, there may not have been a parallel fall in the number of teachers. This chapter does not distinguish between a reduction in class size due to demographic changes or to a deliberate policy decision.
USD converted using PPPs for private consumption
1. Statutory salary (after 15 years of experience) instead of average actual salary (for 25-64 year-old teachers).
2. Lower secondary and upper secondary education are combined for the calculation of the student-teacher ratio.
3. Year of reference for actual salary differs from 2023.
For data, see Table D4.1. For a link to download the data, see Tables and Notes section.
Other findings
In most countries, teachers’ salary cost per student in primary education increased between 2015 and 2023, rising by an average of 20%, driven by demographic changes and/or political decisions. In contrast, the cost for lower secondary education grew more modestly in about three quarters of countries, with an average increase of only 8% over the same period.
Similar levels of expenditure among countries can mask a variety of contrasting policy choices. For example, the Netherlands and Spain have nearly the same salary cost of teachers per primary student, even though teachers’ salaries in the Netherlands are about 40% higher than in Spain. This is partly offset by the significantly longer time a single teacher teaches a full class – 236 additional hours per year – which reduces the number of teachers needed per student.
For a few countries, their ranking changes considerably when teachers’ salary costs per student are expressed as a percentage of gross domestic product (GDP) per capita rather than in absolute USD terms. At the primary level in 2023, Denmark had one of the highest absolute costs (USD 5 781) but ranked only 11th with respect to its relative cost (7.5% of GDP per capita). On average across OECD countries, the salary costs of teachers per student are equivalent to 7.4% of GDP per capita at primary level and 8.9% at lower secondary level.
Note
The analysis is limited to regular education. while special education and adult education are excluded from the scope of the Chapter. The use of actual salaries means that this chapter takes into account the actual level of qualifications and the seniority of the teaching workforce. As the actual salary does not include the employer’s contribution to social security nor pensions, it does not represent the full cost incurred by the employer (i.e. the government). The calculation also includes a full-class adjustment factor for teaching time. The teaching time adjusted by this factor corresponds to the number of hours that a single teacher teaches a full class. If a class is split in two, or two teachers teach a class, this would count as half the teaching time. This adjustment ensures consistency with the existing formulas used to calculate the salary cost of teachers per student (SCS) while capturing the different teaching arrangements teachers face (see Methodology section).
Contribution of each factor to the salary cost of teachers per student
Teachers’ salary cost per student is shaped by four key factors: teachers’ salaries, students’ instruction time, teachers’ statutory teaching time (adjusted using a full-class teaching time factor) and average class sizes. These factors influence salary costs in different ways. The effect of teacher salaries is direct: higher salaries increase the cost per student. The other three factors determine the number of teachers required, assuming a constant number of students. If instruction time increases or teachers’ statutory teaching time decreases, more teachers are needed to maintain existing class sizes. Similarly, reducing class sizes increases the number of teachers required if other factors are constant, which in turn raises salary costs (see Definitions and Methodology sections).
By comparing each of these factors to the OECD average, it is possible to identify how they contribute to any deviation from the average salary cost. For instance, a country’s higher-than-average salary cost may be driven by elevated teacher salaries, longer instruction time, reduced teaching hours, smaller class sizes or a combination of all four. This decomposition allows policy makers to understand not just how much is being spent, but why. Moreover, it highlights the trade-offs involved: modifying one factor may require compensatory adjustments to the others to maintain the same overall cost. This underscores the value of salary cost indicator in evaluating the efficiency and policy orientation of resource allocation within education systems.
Variation in teachers’ salary cost per student by level of education
Different teachers’ salary costs per student at different education levels can highlight significant differences in how countries allocate resources. On average across OECD countries, salary costs are higher in lower secondary education (USD 4 444) than in primary education (USD 3 993). This difference is largely driven by two structural factors: students receive more instructional hours (117 hours more per year), and teachers have shorter full-class teaching hours (44 hours fewer) in lower secondary education. In addition, teachers’ salaries typically increase slightly with the level of education, further contributing to the higher teachers’ salary costs per student. Combined, these factors increase the number of teachers needed per student and, consequently, raise overall salary costs between primary and lower secondary education. Against this, average class sizes increase slightly from 21 students in primary to 23 in lower secondary, which helps offset some of the additional costs. However, this modest increase in average class size is not enough to fully counterbalance the upward pressure from greater instructional demands, and reduced teaching time (Table D4.1, Table D4.2 and Table D4.3)
These averages mask considerable variation across countries, with some showing particularly large differences between education levels. In Austria, for example, the teachers’ salary cost per student rises from USD 6 054 in primary education to over USD 10 127 in lower secondary education – a 67% increase, one of the highest among OECD countries. This reflects a combination of higher teachers’ salaries, shorter statutory teaching hours and longer instruction time, not fully offset by the slightly larger class sizes at the secondary level. Finland, Latvia and Romania also report increases of over 50%, confirming the trend for substantial salary cost rises in a number of countries at the lower secondary level to account for subject specialisation, reduced teaching loads and the greater complexity of the secondary curriculum (Figure D4.1).
Not all countries follow this trend. A few report equal or even lower salary costs per student in lower secondary education compared to primary education. In Iceland, the cost per student is slightly higher at the primary level (USD 5 953) than at the lower secondary level (USD 5 830). In Slovenia, the gap is more substantial: USD 4 432 in primary and only USD 3 133 in lower secondary. Similar patterns can be seen in Chile, Colombia, Costa Rica, Hungary and the Slovak Republic (Figure D4.1)
Among the highest-spending countries are Austria, Flemish community of Belgium, Finland, Germany and Spain, all of which invest well above the OECD average at both levels. These countries generally combine higher teacher salaries with shorter teaching hours that a single teacher teaches a full class or smaller class sizes than the OECD average at both levels. At the other end of the spectrum, Colombia and Czechia, report salary costs per student of below USD 2 400 at the primary level and below USD 3 400 in lower secondary education (Figure D4.1).
Variation in teachers’ salary cost per student relative to countries’ wealth
To better understand the significance of teachers’ salary costs, it is useful to relate them to the size of a country’s economy. Expressing these costs as a share of GDP per capita offers a clearer picture of the economic effort devoted to education. This approach allows for meaningful international comparisons, showing not just how much countries spend in absolute terms, but how that spending aligns with their overall economic capacity. Two countries may invest similar amounts per student, but the relative burden on national resources can differ greatly depending on the size of their economies.
On average across the countries examined, the salary cost of teachers per student represents 7.4% of GDP per capita in primary education and 8.9% in lower secondary education. These averages conceal wide variation across countries, however, and with GDP per capita taken into account, the interpretation of countries’ spending levels can change significantly. Some devote a relatively large share of their national income to teachers’ salary costs despite having modest spending in absolute terms. For example, Costa Rica’s salary cost of teachers is about USD 3 547 per primary student – below the OECD average – but this represents 12.8% of GDP per capita, nearly double the average. In Colombia, the contrast is even sharper: the salary cost of teachers is just USD 2 153 per primary student, but this amounts to 9.8% of GDP per capita, signaling a substantial financial effort relative to economic capacity. Conversely, some high-income countries spend well above the average in absolute terms, but a relatively small share of GDP per capita. For instance, Denmark’s salary cost of teachers is USD 6 111 per lower secondary student – well above average – yet this represents only 7.9% of GDP per capita, below the OECD average. This suggests that while Denmark’s investment in education is high in absolute terms, the financial burden is relatively modest due to its strong economic capacity (Table D4.1).
These comparisons highlight how countries with more limited economic resources may be committing proportionally more of their income to sustaining their education workforce – underlining the importance of considering both absolute and relative measures when evaluating education financing.
It is important to consider the limitations of the methodology used in this chapter when interpreting the results. First, the indicator is calculated using statutory values for teaching and instruction time. This means the results presented in this indicator are theoretical in nature and do not reflect the actual time teachers spend teaching. Indeed, even the concept of teaching and instruction time have become increasingly theoretical in nature, as learning settings become more flexible, making it difficult to accurately measure the amount of time spent on these activities.
Second, by using national figures, the indicator misses the wide discrepancies that may exist within countries. The trade-off between teachers’ salaries and class size, for example, may have very different effects depending on the socio-economic status of students and schools. Moreover, the trade-offs highlighted in this analysis are only a few of the many decisions countries must take when allocating their resources. Countries must also examine potential trade-offs with other investment areas, such as teacher training and school infrastructure, as well as between different levels of education.
Finally, the breakdown of costs between primary and lower secondary has had to be estimated in a few countries because students at both levels are enrolled in the same schools, as in Norway, for example. For these countries, estimation methods may vary, so the breakdown of costs should be interpreted with caution.
Although some of these limitations are difficult to address due to current data availability, there are several possible avenues that would expand the analytical potential of this indicator were more data to become available. One relates to improving the precision when estimating the cost of teachers. To this end, it would also be relevant in the future to take into account the full cost of teachers’ salaries for governments, including costs that do not go directly to teachers, such as employers’ contributions and pensions. This would align the measurement of teachers’ salary costs more closely with the education expenditure data presented in Part C.
Other avenues for potential future development include exploring the link between teachers’ salary costs and school funding formulae, and how the trade-offs associated with teachers’ salary costs may differ across subnational levels of decision making, such as schools, school districts and municipalities.
Different policies in countries with similar spending
Figure D4.2 shows the wide variety of combinations of the four factors across countries and their different effects on the salary cost of teachers per student. The size of the contribution each factor makes to the difference between a country’s salary cost and the OECD average depends on the difference between the factor itself and the respective OECD average. The sum of each factor’s contribution equals the difference in salary cost between that country and the OECD average. For example, the salary cost per student in primary education in Australia is USD 4 958, which is USD 965 higher than the OECD average. This difference reflects the combined effects of several factors: above-average teachers’ salaries increase the cost by USD 1 118; above-average instruction time adds USD 1 021; the above-average number of hours that a single teacher teaches a full class reduces the cost by USD 686; and above-average class sizes reduce it by USD 487 (Table D4.2).
USD converted using PPPs for private consumption
1. Statutory salary (after 15 years of experience) instead of average actual salary (for 25-64 year-old teachers).
2. Year of reference for actual salary differs from 2023.
For data, see Table D4.2. For a link to download the data, see Tables and Notes section.
Higher levels of expenditure on education cannot automatically be equated with better performance by education systems. This can be seen when comparing 15-year-olds’ average performance in mathematics and literacy in the OECD Programme for International Student Assessment (PISA) 2022 with cumulative spending per student between the ages of 6 and 15 in 2022 (see Figure C1.6 in Education at a Glance 2024 (OECD, 2024[1])). This is not surprising, as expenditure figures do not necessarily account for structural factors affecting learning outcomes (such as demographic changes). In addition, countries that spend similar amounts on education may have very different policies and practices. For example, the Netherlands and Spain have nearly the same teachers’ salary cost per primary student, yet the underlying drivers differ considerably. In the Netherlands, teachers’ salaries are about 40% higher than in Spain, but this is offset by significantly longer time a single teacher teaches a full class – 236 additional hours per year – which reduces the number of teachers needed per student. This illustrates how similar spending levels can result from different combinations of salary levels, teaching time and other structural factors.
To illustrate the wide range of policy choices that countries have made despite similar spending levels, the countries shown in Figure D4.2 are divided into four groups with similar teachers’ salary cost per student (see Methodology section).
Group 1: High teachers’ salary cost per student in primary education
This group includes the eight countries with the highest teachers’ salary cost per primary student, with values ranging from USD 5 260 in the Netherlands to USD 6 054 in Austria (Figure D4.2 and Table D4.1). Although the cost is shaped by differences in the four key factors discussed above, these high-spending countries tend to display more alignment across these dimensions than countries in other groups. Notably, all countries in this group pay teachers above-average salaries, and most also report below-average statutory teaching hours (the number of hours that a single teacher teaches a full class) and smaller class sizes – both of which increase the number of teachers needed and thus raise costs. Exceptions include Belgium, Denmark and the Netherlands for the number of hours a single teacher teaches a full class, and Germany and the Netherlands for class size.
Despite these shared characteristics, the main drivers of high salary cost per student differ across countries. In Austria, Belgium, Germany and the Netherlands, the elevated cost is largely due to high teacher salaries, which directly raise per-student expenditure. In contrast, in Iceland and Spain, the high cost is mainly driven by shorter statutory teaching hours. This increases the number of teachers needed to meet instruction time requirements, even though salary levels in these two countries are closer to the OECD average than in the other countries in this group.
These differences illustrate how similar spending levels can result from distinct policy choices and structural arrangements. In some countries, the focus is on competitive teacher compensation to attract and retain talent, while others prioritise working conditions by limiting teaching time in front of a full classroom – both strategies leading to higher salary cost per student.
Group 2: Moderately high or slightly above-average teachers’ salary cost per student in primary education
This group comprises seven countries with above-average teachers’ salary costs per student, ranging from USD 4 229 in Korea to USD 5 165 in Ireland (Figure D4.2 and Table D4.1). In all of these countries except Finland and Portugal the salary cost reflects a trade-off between teachers’ salaries and class size. Australia, Ireland and Korea report above-average teacher salaries, which push costs up, but these are partially offset by above-average class sizes. Conversely, in Slovenia and Italy, teachers’ salaries are below the OECD average, but smaller class sizes drive up the salary cost per student.
A second trade-off, seen in all countries in the group except Ireland and Portugal, lies between students’ instruction time and teachers’ statutory teaching time. In Finland, Korea and Slovenia, below-average instruction time helps contain costs, but this is offset by the shorter number of hours that a single teacher teaches a full class, which increases the number of teachers needed. The reverse is observed in Australia and, to a lesser extent, Italy, where above-average instruction time is balanced by longer teaching hours, limiting the rise in per-student cost.
Group 3: Moderately low teachers’ salary cost per student in primary education
This group includes eight countries with slightly below-average teachers’ salary costs per student, ranging from USD 3 029 in Estonia to USD 3 790 in Greece, compared to the OECD average of USD 3 993 (Figure D4.2 and Table D4.1). All report below-average teachers’ salaries, except Türkiye.
Although there are some similarities, the interaction of instruction time, teaching time and class size varies across the group. In six countries, the slightly below-average salary cost results from a combination of low teacher salaries and shorter teaching hours (adjusted by the full-class factor), which increases staffing needs but keeps overall cost contained due to lower wages. Beyond this, no clear pattern emerges; instead, the four factors often pull in different directions, offsetting one another. In Greece and Poland, lower teacher salaries and shorter instruction time tend to reduce salary cost, but this is partially offset by smaller class sizes and shorter teaching hours, which increase demand for teachers. In Israel, both low salaries and larger class sizes reduce salary cost, but this is counterbalanced by longer instruction time and shorter teaching time, which increase staffing requirements.
These cases show that similar spending levels can arise from different combinations of policy levers, highlighting the varied ways countries manage education cost.
Group 4: Low teachers’ salary cost per student in primary education
This group includes nine countries with significantly below-average teachers’ salary cost per student, ranging from USD 2 153 to USD 2 961 (Figure D4.2 and Table D4.1). The difference from the OECD average ranges from USD 1 032 in France to USD 1 840 in Colombia. In nearly all of these countries, the primary driver of lower cost is low teacher salaries, except in Colombia, where salary levels are closer to the OECD average. In several countries, including Bulgaria, Hungary and Latvia, low salaries alone explain more than USD 1 500 of the difference.
Instruction time also contributes. In six out of the nine countries, students receive less instruction time than the OECD average, which reduces total teaching demand. Only Chile, Colombia and France report average or above-average instruction time, limiting the cost-reducing effect of this factor in their cases.
There is no consistent trend across the group regarding teaching time and class size, although both influence salary cost. In Hungary and Bulgaria – and to a lesser extent in Latvia – significantly shorter teaching hours increase staffing needs, partially offsetting the impact of lower salaries. In contrast, Chile and Colombia benefit from substantially larger class sizes, which reduce the number of teachers needed and help contain salary cost per student despite upward pressures from above-average instruction time, which increases total teaching demand.
Overall, although low teacher salaries remain the dominant factor behind reduced costs in this group, differences in instruction time, teaching time and class sizes also shape national spending levels. These countries achieve similar salary cost outcomes through diverse configurations of policy and resource allocation, often reflecting broader fiscal constraints or strategic priorities in education.
Evolution of average class size and teachers’ salaries
Between 2015 and 2023, the salary cost of teachers per student in primary and lower secondary education increased in constant price terms in all OECD countries except Austria (decrease for both levels), Finland, the Slovak Republic, Slovenia (decrease for lower secondary education) and Poland (decrease for primary education). On average, among countries with data for both years, salary cost increased by 20% at primary level and by 8% at lower secondary level, with significant variations in some countries. The largest increases at the primary level were recorded in Chile (53%), Slovak Republic (51%), and Slovenia (44%), both more than two times the OECD average. At the lower secondary level, Chile (45%) recorded an increase more than five times the OECD average (8%), while Latvia experienced a rise that was more than three times larger (27%) (Table D4.1).
All other factors being equal, teachers’ salary costs per student rise between primary and lower secondary education if teachers’ actual salaries or instruction time increases, or if average class sizes or teaching time decreases. At both levels of education, teachers’ salaries generally have the greatest impact on the degree to which countries’ salary cost of teachers per student diverge from the OECD average (Tables D4.4 and D4.5, available on line).
Given constrained education budgets, policy reforms often involve a trade-off between increasing teachers’ salaries and expanding the teaching workforce. Indeed, when controlling for the total salary cost of teachers, countries with higher teachers’ salaries tend to have larger class sizes (OECD, 2023[2]). In contrast, instruction time and teaching time show relatively limited variation across and within most countries. (Tables D4.4 and D4.5, available on line).
Figure D4.3 plots the changes in teachers’ actual salaries and average class sizes between 2015 and 2023. Over this period, teachers’ salaries in primary education rose in three-quarters of OECD countries with available data, with an average increase of 7% in real terms. Meanwhile, average class sizes remained relatively stable at around 21 students per class. However, this masks considerable variation across countries, with two-thirds of countries showing a decline in average class sizes. Both trends contribute to higher salary costs per student, as rising salaries increase overall expenditure and smaller class sizes require more teachers for the same number of students, intensifying fiscal pressure on primary education systems.
Public institutions only, 2023 constant prices
1. Statutory salary (after 15 years of experience) instead of average actual salary (for 25-64 year-old teachers).
2. Year of reference for actual salary: 2022.
For data, see Table D4.4 (available on line). For a link to download the data, see Tables and Notes section.
Increases in teachers’ salaries have been more pronounced in some Eastern European countries (Czechia, Estonia, Latvia and Lithuania) and in Türkiye, with a more than 28% increase (Figure D4.3). Lithuania is a striking example, as it nearly doubled salaries for primary teachers (from USD 26 584 to USD 50 660) between 2015 and 2023. The substantial increase reflects a deliberate policy effort to attract younger teachers in response to an ageing workforce, as 57% of its teachers are aged 50 or older in primary education (see Table D8.1 in Chapter D8). Despite this, teachers’ salaries in Lithuania remain below the OECD average (Table D4.4, available on line).
Among the two-thirds of OECD countries where average class sizes declined between 2015 and 2023, the most pronounced reductions (close to 10%) were observed in France, Ireland, Italy and Korea (Figure D4.3). In France and Ireland, these reductions reflect deliberate policy efforts to address educational inequality and support disadvantaged communities in primary education (DEPP, 2020[3]; DEPP, 2020[4]; Government of Ireland, 2020[5]). In contrast, the decreases in Italy and Korea appear to be largely driven by demographic trends. Both countries experienced notable declines in primary and lower secondary school enrolment over the last decade (see Figure B2.2 in Education at a Glance 2024), and their school-age populations (5-14 year-olds) are projected to fall further – by 18% in Italy and 37% in Korea by 2031 (OECD, 2024[6]). These examples illustrate how shifts in class size, whether driven by policy choices or structural demographic changes, require countries to strategically adapt their education systems, including how to allocate resources and maintain quality to sustain investments for increased workforce or amid shrinking student populations.
The countries in Figure D4.3 can be grouped into four categories, each corresponding to a quadrant in the chart. Countries in the top-right and bottom-left quadrants have effectively made a trade-off between increasing teachers’ salaries or decreasing average class sizes over this period. Around one-third of countries fall into the top-right quadrant, where both average class sizes and teachers’ salaries increased. This combination reduced the salary cost of teachers per student through larger classes, while simultaneously raising it through higher pay. Notably, the increases in average class sizes in Lithuania (by over 18%) and Latvia (by 8%) only partially offset the significant salary increases of 90% in Lithuania and 32% in Latvia. A few countries, including Ireland, Italy and Portugal made the opposite choice (bottom-left quadrant), with average class sizes falling, somewhat compensated for by falling teachers’ salaries. It is important to note that although these changes have opposite effects on salary cost, they are not necessarily made in response to each other. Indeed, as noted above, for countries like Italy the reduction in the average class size was mainly driven by demographic changes (OECD, 2024[6]).
No particular trade-off between these two variables seems to have been made in the countries in the top-left and bottom-right quadrants. Only Austria features in the top-left quadrant, showing very small differences in average class sizes and reduced teachers’ salaries, slightly pushing down teachers’ salary costs. It is worth noting that Austria may not have pursued further class size reductions during this period, as its average class size is already below the OECD average. In contrast, almost half of the countries fall in the bottom-right quadrant, which reduced average class sizes (by up to 10% in France and Korea) and increased teachers’ salaries (by up to 30% in Czechia), with both measures contributing to a higher salary cost per student.
The data refer to public institutions only. The analysis is limited to regular education. while special education and adult education are excluded from the scope of the Chapter.
Instruction time in this Chapter refers to the amount and allocation of compulsory instruction time that has to be provided in almost every public school and must be attended by almost all public sector students. The compulsory curriculum may be flexible, as local authorities, schools, teachers and/or students may have varying degrees of freedom to choose the subjects and/or the allocation of compulsory instruction time (see Indicator D1 in Education at a Glance 2022).
Teachers’ teaching time is the annual average number of hours that full-time teachers teach a group or class of students, including all extra hours, such as overtime (see Chapter D4 in Education at a Glance 2024). However, it does not necessarily reflect the time teachers spend in front of a full classroom. Therefore, the calculation includes a full-class adjustment factor for teaching time. The teaching time adjusted by this factor corresponds to the number of hours that a single teacher teaches a full class. For instance, if a class is split in two, or two teachers teach a class, this would count as half the teaching time. This adjustment ensures consistency with the existing formulas used to calculate the salary cost of teachers per student (SCS) while capturing the different teaching arrangements teachers face (see Methodology section).
Actual salaries for teachers/school heads aged 25-64 refer to the annual average earnings received by full-time teachers/school heads aged 25-64, before taxes, converted to USD using purchasing power parity (PPP) for private consumption (see Indicator D3). It is the gross salary from the employee’s point of view, since it includes the part of social security contributions and pension-scheme contributions that are paid by the employees (even if deducted automatically from the employees’ gross salary by the employer). However, the employers’ premium for social security and pension is excluded (see Chapter D3 of Education at a Glance 2024).
Class size is calculated by dividing the number of students enrolled by the number of classes. In order to ensure comparability among countries, special needs programmes are excluded. Data include only regular programmes at primary and lower secondary levels of education, and exclude teaching in subgroups outside the regular classroom setting (see Chapter D2).
Theoretical class size refers to the theoretical size of classes given the statutory – or theoretical – values of instruction and teaching time and the student-teacher ratio. It does not reflect the actual average class size in countries.
Compared with previous editions, the formula has been revised to incorporate average class size (instead of theoretical class size) and an estimate of the number of hours a teacher spends teaching a full-class (instead of the number of hours spent teaching either a full-class or a group of students).
The salary cost of teachers per student (SCS) is calculated as:
Where the full-class adjustment factor and theoretical class size are calculated as:
3
Theoretical class size is calculated using statutory instruction time, teaching time and the student-teacher ratio. It is the class size that would result if teachers spent their entire statutory teaching hours individually teaching a full class. In practice, however, classes may be split for some hours, multiple teachers may share a class and teachers often devote part of their statutory teaching hours to other activities. These factors create a gap between the theoretical and the actual average class size. An adjustment factor is then applied to estimate the statutory teaching time, helping to bridge the gap between theoretical and actual class sizes and to estimate the equivalent number of hours a teacher spends teaching a full classroom. When applying the adjustment factor, the interpretation of teaching time changes. For example, an hour of teaching a class that has been split into two would count as 0.5 hours of full-class equivalent teaching time.
The contribution of each factor to the level of the salary cost of teachers per student is analysed by comparing the salary cost of teachers per student in each country to the OECD average then calculating the contribution of these different factors to the variation from the OECD average. This exercise is based on a mathematical relationship between the various factors and follows the method presented in the Canadian publication Education Statistics Bulletin (Éducation Québec, 2003[7]). Using this mathematical relationship and comparing a country’s values for the four factors to the OECD averages makes it possible to measure both the direct and indirect contribution of each of these four factors to the variation in salary cost per student between that country and the OECD average.
Countries are grouped in four clusters with respect to their teachers’ salary cost per student. The cluster analysis allows countries within a group to be more similar to each other than to countries in other groups. On the other hand, countries across groups are as dissimilar as possible.
Please see the OECD Handbook for Internationally Comparative Education Statistics 2018 (OECD, 2018[8]) for more information.
Data on class size referring to the reference year 2023 (school year 2022/23) are based on the UNESCO, OECD and Eurostat (UOE) data collection on education statistics and on the Survey on Teachers and the Curriculum, which were both administered by the OECD in 2023.
Data on instruction time and teacher salaries are from the 2024 Joint Eurydice-OECD data collection and data on teaching time refer to 2024 OECD-INES-NESLI survey on working time of teachers.
References
[3] DEPP (2020), Dédoublement des classes de CP en éducation prioritaire : exploitation des enquêtes auprès des enseignants après deux années de déploiement”, Note d’information No.20.15, Direction de l’évaluation, de la prospective et de la performance, https://archives-statistiques-depp.education.gouv.fr/Default/doc/SYRACUSE/45798/dedoublement-des-classes-de-cp-en-education-prioritaire-exploitation-des-enquetes-aupres-des-enseign.
[4] DEPP (2020), Évaluation de l’impact de la réduction de la taille des classes de CP et de CE1 en REP+, Direction de l’évaluation, de la prospective et de la performance, https://archives-statistiques-depp.education.gouv.fr/Default/digital-viewer/c-50756.
[7] Éducation Québec (2003), “Le coût salarial des enseignants par élève pour l’enseignement primaire et secondaire en 2000-2001”, Education Statistics Bulletin, No. 29, Quebec Ministry of Education, Recreation and Sports, http://www.education.gouv.qc.ca/fileadmin/site_web/documents/PSG/statistiques_info_decisionnelle/bulletin_29.pdf.
[5] Government of Ireland (2020), DEIS Delivering Equality of Opportunity In Schools, Department of Education, https://www.gov.ie/en/department-of-education/policy-information/deis-delivering-equality-of-opportunity-in-schools/.
[1] OECD (2024), Education at a Glance 2024: OECD Indicators, OECD Publishing, Paris, https://doi.org/10.1787/c00cad36-en.
[6] OECD (2024), “How are demographic changes affecting education systems?”, Education Indicators in Focus, No. 87, OECD Publishing, Paris, https://doi.org/10.1787/158d4c5c-en.
[2] OECD (2023), Education at a Glance 2023: OECD Indicators, OECD Publishing, Paris, https://doi.org/10.1787/e13bef63-en.
[8] OECD (2018), OECD Handbook for Internationally Comparative Education Statistics 2018: Concepts, Standards, Definitions and Classifications, OECD Publishing, Paris, https://doi.org/10.1787/9789264304444-en.
To download the data for the figures and tables in this chapter, click StatLink above.
To access further data and/or other education indicators, please visit the OECD Data Explorer: https://data-explorer.oecd.org/.
Data cut-off for the print publication 13 June 2025. Please note that the Data Explorer contains the most recent data.
Table D4.1. Salary cost of teachers per student, by level of education (2015 and 2023)
1. Lower secondary and upper secondary education are combined for the calculation of the student-teacher ratio.
2. Statutory salary (after 15 years of experience) instead of average actual salary (for 25-64 year-old teachers).
3. Year of reference for actual salary: 2022.
4. The OECD average only includes OECD countries and other participants with data for all factors used to calculate salary cost.
Table D4.2. Contribution of various factors to salary cost of teachers per student in primary education (2023)
Note: See Tables D4.4 and D4.5, available on line, for notes on each factor.
1. Statutory salary (after 15 years of experience) instead of average actual salary (for 25-64 year-old teachers)
2. Year of reference for actual salary: 2022.
Table D4.3. Contribution of various factors to salary cost of teachers per student in lower secondary education (2023)
Note: See Tables D4.4 and D4.5, available on line, for notes on each factor.
1. Lower secondary and upper secondary education are combined for the calculation of the student-teacher ratio.
2. Statutory salary (after 15 years of experience) instead of average actual salary (for 25-64 year-old teachers)
3. Year of reference for actual salary: 2022.
a – category not applicable; b – break in series; d – contains data from another column; m – missing data; x – contained in another column (indicated in brackets). For further control codes, see the Reader’s Guide.
For further methodological information, see Education at a Glance 2025: Sources, Methodologies and Technical Notes (https://doi.org/10.1787/fcfaf2d1-en).
Annual salary cost of teachers per student in public institutions, in equivalent USD, converted using PPPs for private consumption, and in percentage of GDP per capita
Note: For notes on this table and a link to download the data, see Tables and Notes section above.
Public institutions only, in equivalent USD, converted using PPPs for private consumption
Note: For notes on this table and a link to download the data, see Tables and Notes section above.
Public institutions only, in equivalent USD, converted using PPPs for private consumption
Note: For notes on this table and a link to download the data, see Tables and Notes section above.