Calculator
How to use the result
Run at least three versions: conservative client count with high usage, expected case, and target scale. If a small increase in variable usage turns contribution negative, redesign the package before selling it.What the calculator does not include
It does not estimate taxes, churn, refunds, sales commissions, founder time, acquisition cost or future vendor price changes. Add those in a full business model before treating contribution as profit.Use the calculator as a planning tool, not a forecast
A useful reseller model should survive more than one optimistic scenario. Run the calculator with fewer clients than you hope to have, higher usage than you expect, and a realistic shared-cost figure that includes software you cannot allocate directly to one account. If the contribution margin becomes negative under modest stress, the offer needs different pricing, tighter usage boundaries, or a lower-cost delivery model before you scale it.
MRR also says nothing about retention by itself. Two offers can show the same monthly recurring revenue while producing very different businesses if one requires heavy support, frequent refunds or constant customer replacement. Pair the MRR result with a simple retention and support model so you understand whether recurring revenue is actually becoming recurring contribution.
Tip: Re-run the model whenever your vendor changes pricing, a new add-on becomes mandatory, or your support load changes materially. Unit economics should be treated as a living operating model, not a launch-day calculation.