Return on ad spend (ROAS) tells you how much revenue a dollar of advertising generates, but a single ROAS number floating in a dashboard does not tell you whether that spend is actually profitable. This calculator turns your gross margin and profit goal into two concrete ROAS thresholds — the bare minimum that keeps you from losing money, and the target that actually earns you the profit you want — plus the maximum you can pay to acquire a single customer.
How it works
Every sale has a gross margin: the percent of revenue left after the direct cost of the product or service, before you spend anything on ads. That margin is the entire pool of money ad spend can draw from, so it sets a hard ceiling on ROAS. Break-even ROAS is simply 100 divided by your gross margin percent — the return where ad spend consumes the whole margin and profit lands at exactly zero.
Target ROAS goes one step further by reserving a slice of that margin for profit before ads get their cut. Subtract your desired profit percent from your gross margin, then divide 100 by what is left. A wider gap between margin and profit target means a lower, easier-to-hit target ROAS; ask for too much profit relative to your margin and the gap can shrink to zero or below, at which point no ROAS is high enough and the calculator reports 0 rather than a misleading negative or infinite number.
Max CPA converts the same margin into a dollar figure instead of a ratio: multiply your average order value by your gross margin percent to find the most you can spend acquiring one order before that order becomes unprofitable at the margin level alone.
Worked example
A store with a 40% gross margin, an average order value of $100, and a 10% desired profit margin works out like this:
- Break-even ROAS: 100 ÷ 40 = 2.5, meaning every ad dollar needs to generate at least $2.50 in revenue just to avoid losing money.
- Target ROAS: 100 ÷ (40 − 10) = 100 ÷ 30 = 3.33, the return needed to actually bank a 10% profit margin on top of covering costs.
- Max CPA: $100 × 40% = $40, the ceiling on what this store can spend to win one order before that order stops paying for itself.
Spend that lands between 2.5x and 3.33x ROAS is still profitable overall but is falling short of the 10% profit goal; anything below 2.5x is losing money on the product itself once ad spend is counted.
How to interpret your result
Break-even ROAS is a floor, not a strategy — campaigns hovering right at that number are funding themselves but not the business. Target ROAS is the number worth optimizing bids toward, since it is the one that actually reflects the profit margin you set out to hit. Max CPA is most useful on platforms and channels that let you cap spend per conversion directly rather than set a return goal, since it expresses the same limit in currency instead of a ratio.
None of these three numbers account for anything outside the margin you entered. If your gross margin figure does not already net out shipping, payment processing fees, returns, or marketplace commissions, real profitability will run below what these results suggest — pad your margin input downward first if those costs are material and not yet subtracted. Treat every figure here as a planning guide for setting bids and budgets, not a guarantee that a campaign hitting the target will always be profitable in a given month, since conversion rates and margins both drift with seasonality and traffic quality.
Methodology & sources
The formulas: breakEvenROAS = 100 / grossMarginPercent, targetROAS = 100 / (grossMarginPercent − desiredProfitPercent) (reported as 0 when that denominator is zero or negative), and maxCPA = avgOrderValue × grossMarginPercent / 100. All three follow directly from the definition of gross margin as the share of revenue available to cover advertising and profit combined.
ROAS itself is a standard e-commerce and paid-media metric; Google Ads describes it as "the average conversion value you'd like to get for each dollar you spend on ads" in its own Target ROAS bidding documentation, which uses the identical ratio this calculator applies to your own margin and profit goals. This tool does not connect to any ad platform or read your actual campaign data — every number here is a target derived purely from the margin, profit goal, and order value you enter, so verify it against your real cost structure before setting live bids.