Break-Even Ad Spend Calculator Methodology
Computes true-ROAS CPA from revenue ÷ ad spend, then caps max CPA at gross-profit break-even when the target ROAS is below break-even.
Amazon FBA is active. Other marketplace modules stay marked as planned until audited.
Computes true-ROAS CPA from revenue ÷ ad spend, then caps max CPA at gross-profit break-even when the target ROAS is below break-even.
Fee schedule/source date: ad-spend economics model reviewed 2026-05-08; compare with live platform CPCs before acting.
Primary source register: Amazon fee schedules · Amazon Revenue Calculator.
Formula
target_cpa_raw = average_order_value / target_roas; break_even_cpa = average_order_value × margin_pct; max_cpa = min(target_cpa_raw, break_even_cpa); break_even_roas = average_order_value / break_even_cpa; max_cpc = max_cpa × conversion_rate
Includes
- Gross margin percentage
- Average order value
- Target ROAS
- Landing-page conversion rate
- True-ROAS target CPA
- Profit-safe max CPA
- Break-even ROAS
- Max CPC
- Flags when target ROAS is below break-even
Excludes
- Creative production cost
- Attribution-window effects
- Returning-customer incrementality
- Platform fees already excluded from margin input
- Coupon/promo funding unless included in margin input
2026 fee-category audit
| Fee component | Status |
|---|---|
| PPC / ACoS impact | modeled in break even ad spend |
| Coupons and promotional discounts | explicitly excluded unless user enters |
Diagnostic output: Margin status, max CPC, true-ROAS target CPA, profit-safe max CPA, break-even ROAS, and flags when the requested ROAS would spend past gross-profit break-even.
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