A useful model.
With visible assumptions.

The calculation, in plain language

Retained orders

Acquired orders × (1 − full-return rate).

Seller revenue

(Price after seller discounts + customer-paid shipping) × retained orders. Platform-funded discounts are assumed to be reimbursed to the seller.

Contribution

Seller revenue − platform charges − creator payouts − ads − product cost − fulfilment − return processing − other per-order costs.

Margin

Contribution ÷ retained seller revenue × 100. Not markup, and not net business profit after overhead and tax.

Maximum creator commission

Contribution before creator payouts ÷ commissionable revenue × 100. This is a break-even ceiling, not an offer recommendation or a target-margin ceiling.

Maximum CPA at target margin

(Contribution before ads − target margin × retained revenue) ÷ acquired orders. The current interface uses a 25% target margin.

Forecast

Current contribution × (1 + chosen monthly volume growth)^(month − 1). Revenue and costs scale together. This is a scenario, not a demand prediction.

The break-even price is found by repeatedly recalculating the same inputs at different selling prices. Category thresholds can make fees discontinuous; for unusual or high-value products, verify the result against your exact fee schedule. Read the worked $40 product example.

Costs and returns

• Creator commission uses the item price after seller discounts on retained orders. Ads, fulfilment and other per-order costs apply to all acquired orders, including returns.
• The return model assumes full-order refunds and recovery of 90% of returned inventory cost. That recovery rate is currently fixed, not a user setting. Recovered stock may not have been resold; inventory value is not cash.
• US refund administration is modelled as 20% of the original referral fee, capped at $5 per returned order. This assumes one SKU unit per order; the official policy applies its cap by SKU type and has exceptions. Multi-unit and partial-refund settlements need a separate reconciliation.
• Fixed and service charges follow the selected market model. Some commission bases include customer-paid shipping; others do not. Account incentives, category overrides and tax treatment can change your actual settlement.
• Business overhead, income tax, financing, duties and cash-flow timing are not separately calculated. Include attributable product-level expenses in the relevant input, without counting them twice.

A default return rate or scenario growth rate is an example, not a market benchmark. Use mature cohorts from your own shop. See the return-cost sensitivity example.