If you’ve read why ROAS doesn’t tell you whether your ads are profitable, you already know that a ROAS figure on its own doesn’t tell you much about whether a campaign is making or losing money. This guide walks through how to calculate the number that does: your break-even ROAS.
The formula
Break-Even ROAS = 1 ÷ Contribution Margin
Where contribution margin is expressed as a decimal (50% becomes 0.50). You can run this directly in our Break-Even ROAS Calculator — this article walks through where the inputs come from.
Step 1: Find your contribution margin, not your gross margin
This is the step most people get wrong. Contribution margin is the percentage of revenue left after every non-advertising cost that varies with the sale — not just the cost of the product.
Start with revenue from one unit or one order, then subtract:
- Cost of goods sold (what you paid to produce or acquire the product)
- Shipping costs you cover
- Payment processing fees
- Marketplace or platform commissions (e.g., a percentage taken by a sales channel)
- Returns and refunds, if they’re predictable and significant
- Fulfillment costs (packaging, pick-and-pack labor, etc.)
What’s left is your contribution margin in dollars. Divide that by revenue to get it as a percentage.
Gross margin, by contrast, typically only subtracts cost of goods sold. If you stop there, you’ll overstate your margin and understate the ROAS you actually need — which can make a losing campaign look profitable on paper.
Worked example
A product sells for $100.
| Line item | Amount |
|---|---|
| Revenue | $100.00 |
| Cost of goods sold | $40.00 |
| Payment processing (3%) | $3.00 |
| Shipping | $4.00 |
| Fulfillment | $3.00 |
| Contribution margin | $50.00 (50%) |
Gross margin here would look like $60 (60%) — revenue minus cost of goods sold only. But the true contribution margin, after every other variable cost, is $50, or 50%.
Step 2: Plug the margin into the formula
With a 50% contribution margin:
Break-Even ROAS = 1 ÷ 0.50 = 2.0
This means you need at least $2 in revenue for every $1 of ad spend just to cover costs. A ROAS of exactly 2.0 is break-even — no profit, no loss, before fixed costs. A ROAS of 3.0 means roughly a third of each advertising-driven dollar of revenue is left over as profit (before fixed costs); a ROAS of 1.5 means every sale driven by that spend is losing money.
Step 3: Compare it to your actual ROAS
Once you know your break-even number, check it against your real ROAS using the ROAS Calculator. If your actual ROAS is below your break-even ROAS, that spend is losing money even if revenue looks healthy. If it’s above, the gap between the two is roughly how much room you have before advertising stops being profitable.
A few things this calculation does not cover
- Fixed costs. Rent, salaries, software subscriptions, and other overhead aren’t included in contribution margin. Break-even ROAS tells you when a campaign stops losing money on a per-sale basis — covering fixed costs requires profit beyond that point.
- Changing costs. Shipping rates, platform fees, and product costs can change. Revisit the calculation periodically rather than treating it as fixed forever.
- Blended attribution. Like ROAS itself, break-even ROAS is only as accurate as the revenue and spend figures you put into it. Make sure both numbers reflect the same time period and the same attribution logic.
Summary
- Calculate your contribution margin using every non-advertising variable cost — not just cost of goods sold.
- Divide 1 by that margin (as a decimal) to get your break-even ROAS.
- Compare your actual ROAS against that number, not against a generic benchmark.
Getting this right turns ROAS from a vague “is this good?” signal into a specific, calculable answer about profitability.