Quick guide
How to use this calculator
- Gather Contribution margin before advertising (%) (0–100) for the same business scenario before calculating.
- Use the same order population and tax/shipping convention for revenue and costs; avoid mixing customer-paid and merchant-paid amounts.
- Apply the displayed break-even roas result to the stated decision only after checking every entered assumption.
Calculation method
Calculation method
Break-even ROAS = 1 ÷ contribution margin rate.
The calculation uses these named inputs: Contribution margin before advertising (%) (0–100). No market rate, benchmark, tax rule, or accounting classification is inserted automatically.
Fixed-decimal arithmetic remains exact through display unless a result is explicitly labelled approximate, such as a square-root inventory quantity.
Ecommerce unit economics
Where the Break-Even ROAS Calculator helps
Calculate the revenue-to-ad-spend ratio implied by an entered pre-ad contribution margin share of 0% to 100%.
Use the result to model the order-level or channel-level economics produced by entered sales, fulfillment, platform, payment, refund, and advertising assumptions.
- Check contribution per order
- Compare two marketplace or fulfillment scenarios
- Stress-test refunds, fees, or advertising cost
Interpretation check
How to audit the result
Recalculate the scenario when any of these inputs changes: Contribution margin before advertising (%) (0–100).
Keep this formula beside the result: Break-even ROAS = 1 ÷ contribution margin rate. Then compare the output with the source records and the calculator-specific assumption below.
- Confirm that all amounts use one currency and reporting period.
- Check that rates, counts, and quantities describe the same population or transaction set.
- Save the entered assumptions with the decision; the result alone is not reproducible evidence.
Worked example
Worked example
A 25% contribution margin gives break-even ROAS of 4.
Break-even ROAS = 1 ÷ contribution margin rate.
Supported inputs
Precision and limits
Visible input limits
Fixed decimals accept up to 30 digits and 12 decimal places and are capped at an absolute value of 1e12 per input. Rates are capped at 1000%; percentage shares and method-specific domains may be narrower.
International scope
No currency, tax jurisdiction, accounting framework, payroll rule, marketplace fee schedule, financing term, or industry benchmark is selected automatically.
Decision boundary
Use the result to model the order-level or channel-level economics produced by entered sales, fulfillment, platform, payment, refund, and advertising assumptions. Results remain arithmetic scenarios, not accounting records, forecasts, valuations, legal interpretations, professional advice, or recommendations.
Calculator-specific assumptions
This is a scenario from visitor-entered values. Keep currencies, periods, accounting classifications, and operating definitions consistent. It is not accounting, tax, legal, investment, or business advice.