Break-Even ROAS Formula: Find Your Advertising Threshold
Calculate break-even ROAS from contribution margin, check a worked example, and see which variable costs to include before setting an advertising target.
Break-even ROAS equals 1 divided by your contribution margin before advertising, expressed as a decimal. A 40% contribution margin requires 2.5× ROAS to cover variable costs and advertising. That threshold leaves nothing for fixed overhead or profit, so it is a starting point for a campaign decision.
Which margin belongs in the formula?
Use the share of revenue left after variable costs other than the advertising being evaluated. Include product cost, payment fees, fulfillment, shipping subsidies and return-handling costs where relevant. These costs determine how much of each sales dollar is available to pay for advertising.
OpenStax explains contribution margin as sales less variable costs. Apply that definition consistently: do not subtract ad spend when calculating the margin and then subtract the same spend again in the campaign model. Our contribution margin guide covers the underlying calculation.
For this model, revenue means sales after discounts and expected refunds, excluding collected sales tax. Do not subtract those refunds again as a variable cost. Keep revenue and variable costs on the same basis. If refunded products can be resold, their recoverable cost differs from a fully lost order.
Work through a $100 order
This hypothetical order has $100 of revenue and $60 of variable costs before advertising. It contributes $40 toward ads and overhead. Spending exactly $40 to acquire that order produces $100 ÷ $40 = 2.5× ROAS and zero contribution after advertising.
| Item | Hypothetical amount |
|---|---|
| Revenue after discounts and refunds | $100 |
| Product cost | $45 |
| Fulfillment and shipping subsidy | $10 |
| Payment and other variable costs | $5 |
| Contribution before ads | $40 |
| Contribution margin before ads | 40% |
| Maximum ad spend at this threshold | $40 |
Calculate the margin as ($100 − $60) ÷ $100 = 0.40. Then calculate break-even ROAS as 1 ÷ 0.40 = 2.5. The percentage equivalent is 250%, not 2.5%. Use the break-even ROAS calculator to repeat the calculation with your own contribution margin.
Leave room for overhead and a target contribution
A higher threshold is needed when advertising must leave a surplus. In the same hypothetical example, requiring $10 per order after ads reduces allowable advertising from $40 to $30. Required ROAS becomes $100 ÷ $30, or approximately 3.33×. That $10 still needs to cover any excluded fixed costs before becoming profit.
At campaign level, contribution after advertising equals revenue × contribution margin before ads − ad spend. For example, $10,000 × 40% − $3,000 = $1,000. The reported ROAS is 3.33×, but the model's $1,000 surplus is the useful next step toward understanding profitability.
What can make the threshold misleading?
The formula assumes a stable product mix and margin. A campaign that sells more low-margin products can report rising revenue while generating less contribution. Recalculate with weighted campaign costs when product mix changes; a simple average of product margin percentages can mislead.
Check the conversion-value definition as well. Google Ads supports different conversion values, so a platform value-to-cost figure is revenue ROAS only when the values represent revenue. Attribution also allocates credit; it does not by itself prove every attributed order was caused by the campaign.
Can every business calculate a finite threshold?
No. If contribution before advertising is zero or negative, there is no positive ad budget that this immediate-order model can recover. Future repeat purchases require a separate, explicit customer-value model rather than silently changing the meaning of revenue.
Use the campaign profitability workbook to record assumptions and compare scenarios. The resources library also contains pricing tools for investigating the costs behind a weak margin.