Break-Even ROAS Calculator: Target ROAS and Max CPA
Start from your price and cost per sale to find the ROAS you need to break even on ads, the higher target ROAS for a profit goal and the maximum CPA. This sets the threshold before you spend; to measure the ROAS a campaign actually achieved, use the return on ad spend calculator.
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Formula
margin = (price - cost per sale) / pricebreak-even ROAS = 1 / marginmaximum break-even CPA = price - cost per saletarget ROAS = 1 / (margin - target profit)maximum CPA for the goal = price x (margin - target profit)
Target profit is a share of ad-driven revenue. Costs should include everything that scales with a sale, such as product, shipping, payment fees and returns.
Worked example
Price 50, cost per sale 30, target profit 10%.
- Margin: 20 / 50 = 40%.
- Break-even ROAS: 1 / 0.40 = 2.5. Maximum break-even CPA: 20.
- Target ROAS: 1 / (0.40 - 0.10) = 3.33. Maximum CPA for the goal: 50 x 0.30 = 15.
Another example
Price 80, cost per sale 52, target profit 5%.
- Margin: 28 / 80 = 35%. Break-even ROAS: 1 / 0.35 = 2.86. Maximum break-even CPA: 28.
- Target ROAS: 1 / (0.35 − 0.05) = 3.33. Maximum CPA for the goal: 80 × 0.30 = 24.
Rules of thumb
The thinner the margin, the higher the ROAS you need: a 50% margin breaks even at 2, a 25% margin at 4 and a 10% margin at 10. Quoted "good ROAS" figures such as 4:1 only make sense next to your own margin.
Common mistakes
- Using product cost only. Include shipping, payment fees, returns and discounts, or the break-even ROAS looks too low.
- Judging by platform-reported ROAS, which can double count conversions that other channels also claim.
- Ignoring repeat purchases. Compare with customer lifetime value before pausing a campaign that loses on the first order.
How it differs
Return on ad spend is the result you measured; break-even ROAS is the bar it must clear. Break-even CPA here is per sale, while the CAC calculator works from your real spend and customer counts.
Frequently asked questions
How do you calculate break-even ROAS?
Break-even ROAS is 1 divided by your profit margin before ad spend. With a price of 50 and costs of 30 the margin is 20 / 50 = 40%, so break-even ROAS is 1 / 0.40 = 2.5: you need 2.50 of revenue for every 1 spent on ads.
What is the maximum CPA I can afford?
At break-even the most you can pay to win one customer is the profit per sale: 50 - 30 = 20. Any acquisition cost above that loses money on the first sale.
How do I get a target ROAS for a profit goal?
Subtract the profit you want, as a share of ad revenue, from the margin and take 1 divided by the result. With a 40% margin and a 10% profit goal that is 1 / 0.30 = 3.33, and the matching maximum CPA is 50 x 0.30 = 15.
Why is there no result when the cost is the same as the price?
With a margin of zero no amount of revenue covers the ad spend, so break-even ROAS would be infinite. The same applies when the profit goal is as large as the margin.
Does this include repeat purchases?
No. It looks at a single sale. If customers buy again, you may accept a lower ROAS on the first order, so compare it with a lifetime value figure before cutting campaigns.
What is the difference between ROAS and break-even ROAS?
ROAS is what a campaign actually returned: revenue divided by ad spend. Break-even ROAS is the minimum ROAS at which the ads cover your costs, 1 divided by your margin. A campaign at 3.0 is profitable when break-even ROAS is 2.5 but losing money when it is 3.5.
What is a good ROAS for ecommerce?
There is no universal number, because it depends on margin. As a rule of thumb, a 25% margin needs a ROAS of 4 just to break even, while a 50% margin needs only 2. Treat 4:1 as a starting point to test against, not as a target.
How do I convert break-even ROAS to break-even CPA?
Multiply the price by your margin: break-even CPA = price ÷ break-even ROAS. With a price of 80 and a 35% margin, break-even ROAS is 2.86 and break-even CPA is 80 × 0.35 = 28. In Excel the ROAS is =1/margin and the CPA is =price*margin.