Start with contribution before advertising
Deduct product cost, shipping, payment fees, and expected revenue lost to refunds from the selling price. What remains is the amount available to cover advertising and profit.
Separate break-even from your target
Break-even ROAS covers the modeled costs. A target ROAS leaves an additional profit margin. If your contribution margin is too low for the target, the calculator tells you it cannot be reached with those assumptions.
Use the result as a planning estimate
The public calculator does not change Google Ads bids, budgets, or GMCMax’s automation threshold. Actual results depend on costs, order mix, attribution, and refund timing.