Countries with the Smallest Class Sizes Worldwide 2026

Countries with the smallest class sizes in the latest comparable international data are mostly education systems where primary classrooms average between 14 and 19 students. The latest comparable international dataset available for a 2026 comparison is not a live 2026 classroom census. It mainly uses reference year 2023, with Croatia and Peru reported for 2022. The data come from OECD’s average class size indicator and the UNESCO-UIS/OECD/Eurostat education statistics collection used in OECD Education at a Glance 2025 [Source-1✅].

Smallest Primary Class Sizes by Country

The smallest reported primary class size in the available dataset is Peru, with an average of 14 students per primary class in all institutions. Costa Rica and Croatia follow at 15 students, while Luxembourg reports 16 students. Several European systems cluster at 17 to 18 students, including Latvia, Greece, Austria, Estonia, Iceland, Italy, Poland, and Slovenia.

The ranking above uses the all institutions column because public and private school coverage differs across countries. Data source: OECD Table D2.3 [Source-2✅].

Full Available Primary Class Size Ranking

The broader ranking shows that most reported primary class sizes fall inside a fairly narrow band. Many systems sit between 18 and 23 students. The OECD average is 21 students per primary class, while the EU25 average is 19 students. These averages are useful reference points, but they do not replace the country-level values.

Table values are average number of students per class in all institutions. Missing and not applicable observations are excluded from the ranking instead of being estimated.

Smallest Lower Secondary Class Sizes

Lower secondary classes are often larger than primary classes because subject-based teaching can change how students are grouped. The smallest reported lower secondary values in the available data are 18 students per class, reported by Latvia, Luxembourg, Poland, and Croatia. Estonia and Finland follow at 19 students.

Primary and Lower Secondary Differences

A small primary average does not always carry into lower secondary education. Costa Rica, for example, reports 15 students per primary class and 29 students per lower secondary class. Peru reports 14 at primary level and 22 at lower secondary level. In contrast, Croatia, Luxembourg, Latvia, Estonia, Finland, and Poland remain below or near 20 students at both levels.

What “Class Size” Means in International Data

Average class size is not the same as the number of students assigned to one teacher. OECD defines class size as the number of students following a common course of study, usually based on the highest number of common compulsory courses. Teaching in subgroups is excluded, and the indicator is limited to primary and lower secondary education because class grouping becomes harder to compare at higher levels [Source-1✅].

The student-teacher ratio uses a different calculation: full-time equivalent students divided by full-time equivalent teachers at the same education level. A country can therefore have a modest student-teacher ratio and still have larger classes, especially when schools use specialist teachers, support staff, small-group teaching, or subject rotation. UNESCO’s glossary also notes that pupil-teacher ratios are not equivalent to average class size [Source-3✅].

Why Some Countries Are Missing From the Ranking

Some large education systems do not appear in the ranking because the relevant average class size value is missing, not applicable, or not reported in the same table column. That does not mean they have large classes. It means the table does not provide a comparable value for the selected indicator. This distinction prevents missing observations from being mistaken for large class sizes.

Countries Not Ranked Because the Average Class Size Value Is Missing

Data Patterns Behind Smaller Class Sizes

Smaller average class sizes usually reflect a mixture of school organization, student population size, teacher supply, school network density, and public-private sector structure. The data do not prove one single cause. A country may have smaller classes because rural schools remain open, because enrolment has declined, because staffing policies preserve class sections, or because schools divide students differently across grades and subjects.

Primary Schooling Shows the Smallest Averages

Primary education often has smaller or more stable grouping because one teacher may stay with the same class for several subjects. This does not happen everywhere. Still, the lowest primary values in the dataset sit well below the OECD average of 21 students. The cluster of 14 to 18 students is therefore a clear low-class-size group among countries with reported data.

Lower Secondary Can Change the Picture

Lower secondary education tends to introduce more subject specialization. Schools may reorganize students for mathematics, languages, science, arts, and optional courses. In many countries this level has larger classes than primary education. Yet several systems keep both levels compact: Croatia, Latvia, Luxembourg, Estonia, Finland, and Poland all report lower secondary averages below 20 students.

Public and Private Values Should Be Read Carefully

Private school class-size values can be much smaller in some systems, but the share of students in private institutions differs by country. The all institutions measure gives a more consistent basis for cross-country comparison because it does not rank systems solely from one school sector. Public-private values remain useful for examining differences within individual countries.

Public, Private, and All-Institution Values

The all-institution value combines public and private institutions where both are reported. In a few countries, the private column is much smaller than the public column. Türkiye is a clear example in the 2023 data: public primary classes average 22 students, private primary classes average 11 students, and all institutions average 21 students. Latvia also reports a low private primary value of 13 students, while the all-institution primary average is 17.

How to Interpret the 2026 Ranking

The 2026 ranking reflects the latest comparable data available for the current comparison, not a 2026 classroom census. International education statistics are published with a reporting delay. The OECD table used here mainly reports the 2022/23 school year, while the OECD Data Explorer entry for average class size was updated in 2026. The reference year should therefore be read alongside each country value rather than assumed to be 2026.

Smaller Class Size Is an Input Indicator

Class size is a learning environment indicator. It is not a direct achievement score, graduation rate, PISA result, or teacher-quality measure. Smaller classes may allow more individual feedback and easier classroom monitoring. Yet education outcomes also depend on curriculum, teacher preparation, school leadership, family background, assessment design, language of instruction, attendance, and many other factors. A low class-size rank should not be read as a full education-system rank.

Country Averages Hide Local Variation

National averages can hide differences between regions, municipalities, school types, urban schools, rural schools, grade levels, and subject areas. A country average of 18 students does not mean every classroom has 18 students. Some classes will be smaller. Some will be larger. The value is still useful because it gives a comparable national-level measure.

Comparable Class-Size Coverage Is Limited

Comparable average class-size data cover fewer countries than broader education indicators. UNESCO and World Bank datasets widely report pupil-teacher ratios, but those values measure staffing rather than the number of students grouped in a class. They can support staffing analysis, but they should not be substituted for average class size when countries are ranked by classroom size.

Most Compact Class-Size Group in the Latest Data

The countries that form the lowest primary class-size group are Peru, Costa Rica, Croatia, Luxembourg, Latvia, Greece, Austria, Estonia, Iceland, Italy, Poland, and Slovenia. Each reports a primary all-institution average of 18 students or fewer. At lower secondary level, the most compact group is Latvia, Luxembourg, Poland, Croatia, Estonia, and Finland, all below 20 students.

The smallest comparable primary class sizes in the latest international data range from 14 to 18 students per class. Countries without comparable average class-size observations remain outside the ranking even when pupil-teacher ratios or other staffing indicators are available from separate datasets.