The break-even ROAS formula is short: break-even ROAS equals 1 divided by your contribution margin. If 40% of every order is left after product cost, shipping, fees and returns, you break even on ads at a return of 2.5 dollars of revenue for every dollar of spend. Below that, each ad sale costs more than it earns. Above it, ads are adding profit.
The formula is easy. Getting the margin right is where most accounts go wrong, and a wrong margin produces a confident, wrong target. This piece walks through what belongs in the margin, five worked examples, how the number changes on Amazon and in lead generation, and how to turn break-even into a target you can actually set in an ad platform. If you want to skip the arithmetic, our break-even ROAS calculator does it from the same inputs.
The break-even ROAS formula.
ROAS is revenue attributed to ads divided by ad spend. Google describes target ROAS as the average conversion value you want for each dollar of ad spend, and shows the calculation as sales divided by spend, multiplied by 100% to express it as a percentage. So a ROAS of 5 and a target ROAS of 500% are the same thing written two ways.
Break-even is the point where the margin on ad-driven revenue exactly pays for the ads. Write contribution margin as a share of revenue (0.40 for 40%). At break-even, revenue times margin equals spend, so revenue divided by spend equals 1 divided by margin. That gives the two forms we use:
- Break-even ROAS = 1 / contribution margin. At a 40% margin: 1 / 0.40 = 2.5.
- Contribution margin = (order revenue minus variable costs before advertising) / order revenue.
- Break-even ROAS as a percentage (the way Google Ads asks for it) = 100 / contribution margin percent. At 40%: 250%.
- Break-even ACOS (Amazon) = contribution margin. At 40%: 40%.
What goes into contribution margin.
Contribution margin is not gross margin from the income statement, and it is not the markup on the product. It is what one more order leaves behind after every cost that scales with that order. Fixed costs such as salaries, rent and software do not belong in it, because one more sale does not change them. Ad spend does not belong in it either, because ad spend is what the formula is solving for.
The variable costs we include for an ecommerce order: product cost landed in the warehouse, outbound shipping you pay (net of any shipping the customer pays), packaging, pick and pack or third-party fulfillment fees, payment processing, marketplace or platform transaction fees, an allowance for returns and refunds, and the cost of any discount or free gift. For a lead business the list is different: materials, crew or contractor labor, sales commission, financing fees and warranty reserve on the job.
Worked example: a single-product store.
Take an $80 product. The numbers below are illustrative, chosen to show the method; replace each line with your own costs. The processing rate and return allowance are assumptions for the example, not quotes from any processor.
| Line | Per order | Share of revenue |
|---|---|---|
| Order revenue | $80.00 | 100% |
| Product cost | $28.00 | 35.00% |
| Outbound shipping | $9.00 | 11.25% |
| Payment processing (assumed 3%) | $2.40 | 3.00% |
| Pick, pack and packaging | $4.00 | 5.00% |
| Returns allowance (assumed 5%) | $4.00 | 5.00% |
| Contribution before ads | $32.60 | 40.75% |
| Break-even ROAS | 1 / 0.4075 = 2.45 | 245% in Google Ads terms |
At a ROAS of 2.45, every dollar of ad spend brings in $2.45 of revenue, and 40.75% of that is $1.00, which pays for the ad and nothing else. At a ROAS of 3.0 the same dollar leaves about $0.22 of profit. At 2.0 it loses about $0.19.
Worked examples: discount codes and repeat buyers.
Discounts. Run the same product with a 15% code. Revenue drops to $68. Processing and the returns allowance shrink a little because they scale with price ($2.04 and $3.40), but product cost, shipping and fulfillment do not move. Variable costs come to $46.44, contribution is $21.56, and the margin is 31.7%. Break-even ROAS jumps from about 2.45 to about 3.15. A promotion that looks like a small price change can raise the bar for every campaign running alongside it, which is why we recalculate before a sale goes live rather than after.
Repeat buyers. If customers reorder, the first order is not the whole story. Say a $60 first order leaves $20 of contribution and you expect, from your own cohort data, another $30 of contribution over the next twelve months. Break-even on the first order alone needs a ROAS of 3.0 (60 / 20). If you are willing to wait twelve months to be paid back, you can afford up to $50 to acquire the customer, which is a first-order ROAS of 1.2. Both numbers are valid. The choice between them is a cash decision: how long can the business carry the gap, and how confident are you in the repeat rate. We set the payback window first and the ROAS target second.
“A ROAS target without a margin behind it is a guess with a decimal point.”
Break-even for lead generation.
Lead businesses rarely see revenue in the ad platform, so the same logic runs through cost per lead. Break-even CPL equals the share of leads that become paying jobs multiplied by the contribution on an average job. A remodeler with a $6,000 average job, 40% contribution before marketing, and 20% of leads turning into jobs breaks even at $480 per lead (0.20 times $2,400).
Expressed as ROAS, that is $1,200 of expected revenue per lead divided by $480, or 2.5, which is again 1 divided by the 40% margin. The formula holds; the hard part is feeding it real close rates by lead source. If you import offline conversions with job values from your CRM, Google Ads can bid on value instead of form fills. Our break-even CPL calculator runs the lead version.
Break-even ROAS and ACOS on Amazon.
Amazon reports ACOS, advertising cost of sales, which it defines as ad spend divided by attributed sales. That is the inverse of ROAS: a ROAS of 4 is an ACOS of 25%. Amazon's own guidance makes the point that there is no universal good ACOS; to stay profitable, ACOS has to stay below your margin.
So break-even ACOS equals contribution margin, with Amazon's referral fee and fulfillment fees included in the variable costs. If a product keeps 30% after those fees and its landed cost, break-even ACOS is 30% and break-even ROAS is about 3.33. One caution: Amazon attributes Sponsored Brands sales at the brand level and Sponsored Products sales at the promoted product level, so a campaign's ACOS can include sales of other products with different margins. Use a blended margin for brand campaigns.
From break-even ROAS to a target ROAS.
Break-even is the floor, not the goal. To build profit into the target, subtract the profit you want per order (as a share of revenue) from the margin before dividing: target ROAS = 1 / (contribution margin minus desired profit share). Using the $80 example, a 40.75% margin and a goal of keeping 10% of revenue as profit gives 1 / 0.3075, a target ROAS of about 3.25, or 325% in Google Ads.
Two adjustments before you type that number into a bid strategy. First, platform-reported revenue is not the same as revenue in your store. Each platform counts conversions under its own attribution rules, and the same order can be claimed by more than one. Compare ad-reported revenue to store revenue over the same period and scale the target if the platforms over-report. Second, a target set far above recent performance can choke delivery; we move targets in steps and watch volume alongside efficiency. Teams that want help running this across channels can see how we approach paid media management.
Mistakes that make the number wrong.
If you sell online and want this built into how campaigns are set and reviewed, our ecommerce and Amazon practice starts every account from these numbers. To talk about your account, hire Theory Road.
What is the break-even ROAS formula?
Break-even ROAS equals 1 divided by contribution margin, where contribution margin is the share of each order left after all variable costs except advertising. A 40% margin breaks even at a ROAS of 2.5, or 250% as Google Ads expresses it.
Is break-even ROAS the same as target ROAS?
No. Break-even is the point where ads neither make nor lose money. A target ROAS should sit above it by the profit you want per order: target ROAS equals 1 divided by margin minus your desired profit share.
How do I convert break-even ROAS to break-even ACOS?
ACOS is the inverse of ROAS, so break-even ACOS equals 1 divided by break-even ROAS, which is the same as your contribution margin. A 2.5 break-even ROAS is a 40% break-even ACOS.
Should break-even ROAS include fixed costs like salaries and software?
No. Fixed costs do not change with one more order, so they stay out of contribution margin. They are covered by the profit you build into the target above break-even.