2019-20 is the most recent year we have published data for on the DES website. Class data, including average class size, for the academic year 2020-21 will be available in June 2021.
This figure is based on mainstream classes in mainstream schools and are collated from the relevant Class Size tables published on the DES website and can be found at the link below;
In post-primary schools pupil enrolments vary by subject and so the concept of average class size does not apply. Furthermore enrolments of pupils per subject is available at a school level only so average class size per subject is not available.
With regard to how Ireland compares to other EU member states, please find attached most recent OECD data in relation to class size, 2017/2018. This table also includes individual EU member state (23 EU states are members of the OECD) data as well the OECD & EU 23 average class sizes. As per explanation above this data is for primary schools only.
OECD class size 2017