How roas calculator works
ROAS — return on ad spend — is the gross revenue a campaign generates divided by what the campaign cost. A campaign that spent $3,000 and drove $12,000 of revenue has a ROAS of 4 (often written 4:1 or 400%). It is the fastest headline number for judging a paid campaign, and the one ad platforms are happiest to show you.
The catch is that revenue is not profit. A 4:1 ROAS on a product with a 40% gross margin means $12,000 of revenue carried $4,800 of gross profit against $3,000 of spend — genuinely profitable. The same 4:1 on a 20% margin yields $2,400 of gross profit against $3,000 of spend — a loss wearing a flattering number.
That is why the calculator derives the break-even ROAS from your gross margin: break-even ROAS = 100 ÷ margin percent. At a 25% margin you need a 4:1 ROAS just to break even; at 40% you need 2.5:1. Enter your margin and the tool marks the campaign profitable, break-even or unprofitable, and shows the headroom between actual and break-even ROAS.