"Small classes, personal attention" is on almost every language school website. It is also, run carelessly, the thing that closes them.
The arithmetic is not complicated, and most owners have never done it for their own school.
Do it once, for one class
Take a real class. For one session, add up what it costs you:
- Teacher cost for the session, including any preparation you actually pay for
- Room cost — rent for the building divided down to that room for that hour
- A share of everything else: front desk, marketing, software, utilities
That last one is where people go wrong. Leaving out overhead makes every class look profitable and hides the fact that the school is not.
Divide by the number of students, and compare it to what one student pays per session.
Most small schools find break-even lands somewhere between four and six students. Yours may differ — but your number, on real figures, is more useful than any benchmark.
The marginal student is where the money is
Once the class is running, the next student costs you almost nothing. No extra teacher, no extra room, marginally more paper.
Which means the gap between a class of six and a class of nine is close to pure margin. It also means that a class of three, which feels like a small problem, is often losing money on every session it runs, quietly, all term.
Set a floor and enforce it
Decide the minimum size at which a class runs, and decide it before enrolment rather than in the week the class is due to start.
Running a class of two because you feel bad cancelling is a decision to subsidise those two families with money the other classes earned. Occasionally that is the right call — a strategic level, a new market, a family you want to keep. Make it knowingly, not by default.
The alternative to cancelling is usually merging, and it is worth setting up so you can: aligned levels, aligned timetable slots, so a class of three and a class of four are actually combinable rather than nominally combinable.
And set a ceiling you believe in
The maximum is a marketing promise, so it has to be real. A school that advertises "maximum 8" and runs 11 when demand is high has not increased its margin — it has taught its most engaged parents that the promises are approximate.
Cap it, and when a class fills, open another one or start a waiting list. A waiting list is a much better problem than a diluted class.
The class you should worry about is not the full one. It is the one with four students that has been running all term because nobody looked.
Look at it monthly
Class-level enrolment against your break-even, once a month, is a ten-minute review that pays for itself. See five numbers to look at every Monday for the rest of the set.