ROAS is revenue divided by spend
Return on ad spend is the revenue a campaign produced divided by what the traffic cost. A $15,000 return on a $5,000 spend is 3.0x, which is the headline advertisers quote and the number ad platforms report by default.
It is a ratio, so on its own it says nothing about profit: 3.0x on a 40% margin is a good campaign, and 3.0x on a 20% margin is a much thinner one. Ad spend of zero returns zero rather than an infinite multiple, which is the honest answer for a campaign that never ran.
Profit is revenue times margin minus spend
Profit is revenue multiplied by the product margin - the gross margin after the cost of goods but before the ads - and then the ad spend is subtracted. At a 40% margin, $15,000 of revenue is $6,000 of gross profit, and $5,000 of spend leaves $1,000.
Break-even ROAS is one divided by the margin, so a 40% margin needs 2.5x just to cover the spend and a 25% margin needs 4.0x. The table prints gross profit, the subtraction and the net result, plus net margin on revenue, because a positive ROAS below that line is a campaign quietly losing money while the headline looks healthy.
Use the number that matches the decision
ROAS answers whether the media was bought efficiently; net profit answers whether the campaign made money. Audits and benchmarks want the first, and the decision to increase a budget wants the second, which is why both are on the page rather than one standing in for the other.
Scaling a profitable campaign multiplies the profit, and scaling an unprofitable one multiplies the loss. Reading only the multiple is how a campaign that returns three dollars for every dollar spent still ends the quarter down, and the note under the result spells out the break-even multiple for your own margin.
Blended numbers hide the weak channels
A blended ROAS can look healthy while one channel inside it runs at a loss, and a strong average is exactly what that channel needs to stay hidden. The check has to be run per channel, and separating new-customer spend from return-customer spend is what shows which part deserves more budget.
The calculator prices only the campaign in front of it, so the discipline lies in how it is applied: one run per channel rather than one run on the blended total. An average dilutes a loss without removing it, and the page has no way to know which rows were folded into the number you typed.
ROAS, contribution margin and the breakeven multiple
The breakeven ROAS is one divided by the contribution margin. At a 40% margin, 2.5x returns exactly the ad spend; at 25% it is 4.0x; at 60% it is 1.67x. A 3.0x campaign on a 40% margin keeps $1,000 of the $15,000 of revenue it produced, and the same 3.0x on a 25% margin loses $1,250.
Convert the multiple back into cost per order and the same campaign reads differently: $5,000 for 100 orders is a $50 cost per acquisition, and at a $75 average order value with a 40% margin each order contributes $30 - so the campaign buys $30 for $50. That is what a 1.5x looks like from the order side, and it is the number a merchandiser can act on.
Blended ROAS hides the losers. Two campaigns at 5.0x and 1.2x average to 3.1x on equal spend, and at a 40% margin the second one is destroying money while the average says the account is healthy. Judge each ad set against 2.5x first, then look at the blend.
Attribution flatters paid traffic: retargeting reaches people who were going to buy anyway, and a share of every reported order would have happened without the ad. If a fifth of the attributed revenue is organic, a 3.0x becomes 2.4x - below the 2.5x breakeven at a 40% margin, and that is the difference between scaling and stopping.
Scale on marginal ROAS, not average. The first $5,000 often returns 4.0x and the next $5,000 returns 2.0x; averaging them at 3.0x hides that the last dollar is losing money, and the last dollar is the one that sets the budget.
Cash and time are the last filter: a 3.0x on a 30-day payback still needs working capital for inventory and ad bills, and a 4.0x that pays back in 90 days can starve a growing store. ROAS measures the return, not the speed of it.
Finally, hold the number against a target the business set in advance. A 3.0x is good news against a 2.5x floor and bad news against a 3.5x plan, and a campaign judged after the fact against whatever the account happened to do will always find a story that fits. Write the floor down before the flight starts.
One structural caveat: this page prices a single campaign at a time. Feed it the blended account total and it will report a blended multiple, which is the average that hides the losers; feed it one channel at a time and the breakeven line does the work.
Danfio