Your unit economics (per order)
Repeat purchases (optional)
Leave orders per customer at 1 to see first-order economics only. Use a repeat rate you have measured, over a window you trust.
Enter your numbers, then click Calculate.
Result
Where each order's money goes
| Line | Per order |
|---|
Scenario table: ROAS and CPA needed for each profit margin
Margin is profit as a share of the revenue the ad platform reports. “Not reachable” means that margin cannot be made at any ROAS with these costs.
| Net margin | Max CPA, first order | Target ROAS, first order | Max CPA, LTV | Target ROAS, LTV |
|---|
Sensitivity: break-even ROAS as returns and cost of goods move
Rows are return rates, columns are changes in cost of goods. First-order break-even.
The same grid on the lifetime-value basis.
Check a campaign against your break-even
Use the spend and the purchase revenue your ad platform reports for the same period.
Whole-business check (MER)
MER vs platform ROAS
Platform ROAS is the purchase value an ad platform credits to its own ads divided by what you spent there. Two platforms can both claim the same sale, and view-through and returning-customer credit inflate it. MER (marketing efficiency ratio) is all your store revenue divided by all your ad spend; it cannot double count, but it includes organic and repeat sales, so it flatters any single campaign.
Use platform ROAS to compare campaigns inside one account. Use MER to decide whether the business as a whole is paying for its advertising, and compare both with the break-even above. If MER is comfortably above break-even while platform ROAS is below it, attribution is probably undercounting; if platform ROAS is above break-even but MER is below it, the platforms are probably claiming sales you would have made anyway.
How it is calculated
Reported revenue R = price × (1 − discount) + shipping charged. A share of orders is refunded in full, so kept revenue is R × (1 − return rate). The platform fee is charged on kept revenue; the payment fee (% of R plus a fixed amount) is charged on every order and is not returned on a refund. Cost of goods is spent on every order, less the share of returned units you can resell; shipping is paid on every order and return shipping on refunded ones.
Contribution = kept revenue − platform fee − payment fee − cost of goods − shipping. Max CPA = contribution. Break-even ROAS = R ÷ contribution. For a margin target m, max CPA = contribution − m × R and target ROAS = R ÷ that. On the LTV basis a customer places n orders; each of the n − 1 repeat orders adds the repeat-order share of first-order contribution, and the margin is measured on n × R. The platform still reports only the first order, so LTV ROAS is R ÷ lifetime contribution.
Not modelled: sales tax, fixed overhead, creative and agency costs, subscription churn curves, new versus returning customer mix inside attributed sales, cash-flow timing and payment-reserve holds, and ad platform attribution windows. Unverified: checked against hand-worked examples and identity tests on invented data, not against any real store. Treat the output as a planning estimate.
Common questions
What is break-even ROAS?
Break-even ROAS is the return on ad spend at which an ad campaign earns exactly zero profit after the product, shipping, fees and refunds. It equals the revenue per order divided by the contribution per order, so a product that keeps 40 cents of every reported dollar before ads breaks even at 2.5x. Below it each ad dollar loses money on the first order; above it the campaign is profitable.
How do I calculate maximum CPA?
Maximum cost per acquisition is the contribution per order: the price after discounts, minus refunds, platform and payment fees, cost of goods and shipping. You can spend up to that much to win one order and still break even. Spend less to leave profit; to hit a margin target subtract the profit you want per order.
What ROAS do I need for a 20% profit margin?
Work out the contribution per order, subtract 20% of the revenue the platform reports for that order, and divide the reported revenue by what is left. The scenario table does this for 0%, 10%, 20% or any margins you type. If your contribution margin is under 20% the target cannot be reached at any ROAS and the table says so.
Should I include repeat purchases and lifetime value?
If customers reliably come back, yes, because the first order does not have to repay the whole ad cost. Enter the average total orders per customer over the period you trust and what a repeat order earns compared with the first. The tool shows both views: the first-order break-even that protects cash, and the LTV break-even that shows the most you could pay if repeat behaviour holds. Be conservative with repeat rates you have not measured.
What is the difference between MER and platform ROAS?
Platform ROAS is revenue the ad platform attributes to its own ads divided by what you spent there. MER, marketing efficiency ratio, is all store revenue divided by all ad spend across every channel, including organic and repeat sales. MER is the steadier measure of whether the business as a whole is paying for its advertising; platform ROAS is useful to compare campaigns inside one account but is inflated by attribution overlap and view-through credit.
Why does my return rate matter so much for ROAS?
A refunded order gives the revenue back but the ad money, the outbound shipping and usually the payment fee are already gone. A product with 30% returns needs a much higher ROAS than the same product with 5%, and the sensitivity table shows how fast break-even climbs as returns and cost of goods move.
Is my pricing or cost data sent anywhere?
No. Every figure is calculated in this browser tab. Nothing is sent to a server, there are no accounts or cookies, and nothing you type is saved. It works offline once the page has loaded.