How to use this calculator
- Enter or choose number of students.
- Enter or choose teachers (full-time equivalent).
- Enter or choose target students per teacher.
- The students per teacher updates as you type. Use Copy result or Share to keep it.
Method
Students per teacher = Students ÷ FTE teachers; Teachers needed = ⌈Students ÷ Target⌉
- FTE teachers
- full-time-equivalent teaching staff
- Target
- the maximum students per teacher you must meet
Worked example
- 600 ÷ 24 = 25 students per teacher (25 : 1).
- At 20 : 1, 600 ÷ 20 = 30 teachers are needed.
- 30 − 24 = 6 more teachers.
With 24 teachers for 600 students the ratio is 25 : 1; reaching 20 : 1 needs 6 more teachers.
What the result means
The pupil–teacher ratio is not the same as class size: teachers also have planning time and non-class duties, so average classes are usually larger than the ratio.
Assumptions and limits
- Teachers are counted as full-time equivalents.
- Whether support staff, heads or specialists count as teachers depends on the reporting rules you follow.
Questions
Is pupil–teacher ratio the same as class size?
No. Class size is students in one room; the ratio spreads all students over all teachers, including those not teaching at that moment.
How do I count part-time teachers?
Use full-time equivalents: a teacher working half a full timetable counts as 0.5.