Count all of them,
for every product.
Line five is where comparisons most often go wrong, because it differs per product and schools assume it is constant. A platform that includes live video, a website and payments leaves a school needing only accounting; a scheduling-and-billing tool leaves it needing video, a website builder, forms and possibly a separate teaching tool. Those are real subscriptions with real annual costs, and a comparison that counts only the platform subscription silently credits the narrower product with everything it does not do.
Administrator hours
are money.
When two systems do not share a student record, somebody becomes the integration: re-typing a class change into the billing tool, reconciling the register against the invoice at month end, updating a parent's email in three places. In a small school that somebody is the administrator or the owner, and the hours are invisible because nobody bills for them.
Put a number on it anyway. As an illustration with round figures: two hours a week of reconciliation, at a notional €25 an hour, is €2,600 a year — larger than many of the subscriptions being compared, and it recurs for as long as the arrangement does. Halve it and you have found more money than most negotiated discounts. This is the honest financial case for consolidation, and it is stronger than any feature argument: not that one platform is better at scheduling than a specialist, but that the specialist's excellence is paid for weekly in somebody's evenings.
Estimate your own figure rather than using ours. Ask whoever does the reconciling to note, for two weeks, the time they spend moving information between systems. It is usually more than they expected and it is the most persuasive number in the whole evaluation.
Two products,
same school, year three.
Illustrative round numbers, for a school with 300 active students and €300,000 of annual tuition. Product A is a cheaper subscription with a percentage of tuition and a narrower scope; Product B is a higher subscription with no revenue share and a wider scope. The point is the shape, not the specific figures — put yours in.
Product A wins the subscription comparison by a factor of two and a half and loses the real one by roughly the same margin, entirely because of two lines: the percentage of tuition and the administrator hours. Neither appears on a pricing page. Both are knowable before signing, and both take minutes to estimate.
Read it the other way too, because the arithmetic is honest in both directions: at eighty students with €60,000 of tuition, Product A's percentage is €1,500 and its total lands well below Product B's. Small schools genuinely are better off on revenue-share pricing, which is why it exists. The decision is about which school you will be in three years.
Price the door
while you can still choose.
Leaving a platform costs export work, data cleaning, importing elsewhere, a term of parallel running and re-training. For a small school that is days of work and some disruption — manageable, if the export exists. Where it does not, the cost is not days; it is that the decision is no longer yours to make, and vendors know this even when they never exploit it.
So price the exit at the start, when you have leverage: get in writing that you can export every student, enrolment, payment and attendance record in a documented format, ask to see an example export during the trial, and check that the commitment is in the contract rather than the marketing. The buyer's guide covers migration in more depth; for the cost sheet, it is enough to know whether the line is "a few days" or "unknown".
Twenty minutes,
once, before you sign.
Two disciplines make it useful. Fill it in for every shortlisted product on the same day, with the same assumptions, because the temptation is to be generous to the product you liked. And do it before the final demos rather than after, so that the number informs the conversation instead of justifying a decision already made.