Work out coupon stacking value instantly with clear inputs, formula shown and shareable results.
When a percentage coupon and a fixed-amount coupon stack, the order matters. Applying the percentage first leaves a larger base for the fixed deduction, so it always gives the lower total — the difference is exactly the percentage times the fixed amount.
Coupon order
percentage first: (T x (1 - p)) - F; fixed first: (T - F) x (1 - p); difference = p x F
Percentage first, then the fixed amount. The saving difference is the percentage multiplied by the fixed coupon value — 1.50 on a 15% and 10 combination.
Rarely. Most checkout systems apply a fixed sequence, but knowing the difference tells you whether it is worth asking.