Seller guide
How do I calculate coupon ROI after marketplace fees?
Compare a discounted period with a genuinely comparable baseline using contribution—not revenue—and count the discount, redemption fees, fixed fees, and campaign spend.
Choose a baseline that can survive comparison
Use the same product and a comparable number of days, and note stockouts, seasonality, ad changes, and price changes that make the periods different. A previous 28-day period is not automatically a valid control. The math can describe the difference, but it cannot prove the coupon caused it.
Compare contribution instead of sales revenue
For the baseline, subtract product, fulfillment, other variable costs, and referral fees from list-price revenue. For the deal, apply the discount and recalculate price-based fees before subtracting the same cost stack plus any per-redemption charge. More revenue can still mean less contribution.
Make the promotion investment explicit
Count the customer discount across discounted units, per-redemption charges, the fixed participation fee, and any campaign spend. Incremental contribution is deal-period contribution minus baseline contribution. Divide that change by total promotion investment for an incremental ROI percentage whose inputs a reviewer can audit.
Calculate the lift required to break even
Take baseline contribution plus fixed deal and campaign costs, divide by discounted contribution per unit, and round up. Compare that break-even unit count with baseline units. If discounted contribution per unit is zero or negative, additional discounted volume cannot recover the fixed costs.
Tools that help with this
- Coupon and Deal Incremental ROI Calculator ($0.25) — Calculate contribution lift, promotion investment, ROI, and break-even units
- Marketplace Promotion Profit Guard ($0.25) — Screen prospective coupon and markdown scenarios before activation
- Marketplace Price Change Break-Even Analyzer ($0.25) — Compare direct price changes against current contribution
Every paid output is a draft for your review before you publish, appeal, or activate anything. Friday does not access your seller account.