Break-even ROAS & ACOS Calculator

This tool converts the margin available before advertising into campaign thresholds. It shows break-even ACOS and ROAS, then tightens both metrics to preserve a chosen net margin after advertising spend.

Enter gross or contribution margin after product, fulfillment, payment and other variable costs but before advertising. Then enter the net margin you want left after ads; the target must be smaller than the starting margin.

At a 40% contribution margin, break-even ACOS is 40% and break-even ROAS is 2.50x. Preserving a 10% net margin leaves 30% of revenue for ads, requiring ACOS at or below 30% and ROAS at or above 3.33x.

Break-even ACOS equals the pre-ad contribution margin. Break-even ROAS is one divided by the margin expressed as a decimal. At those thresholds, advertising consumes all contribution profit and net profit is zero.

Maximum ACOS for a target equals contribution margin minus desired net margin. Required ROAS is one divided by that remaining advertising allowance, producing a stricter threshold than simple break-even.

Use the margin remaining after every non-ad variable cost, not gross revenue or markup on cost. If returns, discounts or marketplace fees are material, include representative allowances before calculating ad limits.

The model assumes costs are stable percentages of revenue and does not prove attribution or incremental demand. Fixed overhead and cash-flow timing need separate analysis. Calculations remain local and inputs are not uploaded.