ROAS Calculator
Return on ad spend, ACOS & ad profit
$4,000 of revenue from $1,000 of ad spend is a 4x ROAS, a 25% ACOS and $3,000 left after ad costs, before cost of goods. Enter your own revenue and spend, then add your gross margin for the one number that decides whether ads pay: the break-even ROAS below which every extra dollar of spend loses money.
What ROAS tells you, and what it hides
ROAS (return on ad spend) is revenue divided by ad spend. A 4× ROAS means every $1 of ads brought in $4 of revenue. ACOS (advertising cost of sale) is the same relationship inverted and expressed as a percentage, which is the convention on Amazon.
The trap is in the first word of the definition: ROAS measures revenue, not profit. A 4× ROAS is excellent at a 60% margin and a straight loss at a 20% margin, and nothing in the ratio itself tells you which situation you are in. That is why the gross margin field above matters more than the headline number.
ROAS to ACOS conversion
Working as an acos calculator and an ad spend calculator at once, the tool reports both figures from the same two inputs.
They are reciprocals: ACOS = 1 ÷ ROAS, expressed as a percentage. If you work across Google and Amazon you will convert between them constantly.
| ROAS | ACOS | Meaning |
|---|---|---|
| 1× | 100% | Revenue exactly equals spend |
| 1.5× | 66.67% | Losing money at most margins |
| 2× | 50% | Break-even at a 50% margin |
| 2.5× | 40% | Break-even at a 40% margin |
| 3× | 33.33% | Break-even at a 33% margin |
| 4× | 25% | Break-even at a 25% margin |
| 5× | 20% | Break-even at a 20% margin |
| 10× | 10% | Break-even at a 10% margin |
Read the right-hand column carefully, because it is the whole point. Break-even ROAS is simply 1 ÷ your gross margin. The ROAS and the margin that break even against each other are numerical mirrors: at a 25% margin you need a 4× ROAS just to stand still.
Break-even ROAS by gross margin
What a 4× ROAS on $4,000 of revenue and $1,000 of spend actually earns you, at each margin:
| Gross margin | Break-even ROAS | Gross profit | Net after $1,000 ads | Per $1 spent |
|---|---|---|---|---|
| 10% | 10× | $400 | −$600 | −$0.60 |
| 20% | 5× | $800 | −$200 | −$0.20 |
| 25% | 4× | $1,000 | $0 | $0.00 |
| 30% | 3.33× | $1,200 | $200 | $0.20 |
| 40% | 2.5× | $1,600 | $600 | $0.60 |
| 50% | 2× | $2,000 | $1,000 | $1.00 |
| 60% | 1.67× | $2,400 | $1,400 | $1.40 |
| 80% | 1.25× | $3,200 | $2,200 | $2.20 |
The same campaign is a $600 loss for a low-margin retailer and a $2,200 win for a software business. This is why "what is a good ROAS" has no universal answer, and why any benchmark quoted without a margin attached is worthless.
Worked example: a 4× campaign at a 40% margin
$4,000 of attributed revenue on $1,000 of spend, with a 40% gross margin — the calculator's default scenario:
| Output | Working | Result |
|---|---|---|
| ROAS | 4,000 ÷ 1,000 | 4× |
| ACOS | 1,000 ÷ 4,000 | 25% |
| Profit after ad spend | 4,000 − 1,000 | $3,000 |
| Break-even ROAS | 1 ÷ 0.40 | 2.5× |
| Gross profit | 4,000 × 40% | $1,600 |
| Net profit after ads | 1,600 − 1,000 | $600 |
| Profit per $1 of ad spend | 600 ÷ 1,000 | $0.60 |
Notice the gap between "profit after ad spend" at $3,000 and real net profit at $600. The first ignores the cost of the goods you sold. Dashboards report the first number; your bank account reflects the second.
Where ROAS sits in the funnel
ROAS is one link in a chain, and reading it on its own is what makes it misleading. CPM sets the price of reach; conversion rate decides how much of that reach turns into customers; CAC is what those customers ended up costing; and lifetime value is what they are worth once they stay. Cheap clicks with a weak conversion rate still produce an expensive CAC, which is why a low CPM proves nothing by itself.
The number that decides whether the whole machine pays is the LTV:CAC ratio, and the usual target is 3:1. Below 1:1 you lose money on every customer won; far above 4:1 normally means underspending rather than excellence. A campaign can post a strong ROAS and a poor LTV:CAC at the same time, and that combination is a warning rather than a win — it is the most common way an account that looks profitable on the dashboard quietly drains the business. Know your break-even point before scaling, so the money comes out of profit rather than hope.
ROAS vs CAC vs ACOS
Three metrics that describe the same spending from different angles. They answer different questions and you generally need more than one.
| Metric | Formula | Answers | Best for |
|---|---|---|---|
| ROAS | revenue ÷ spend | How much revenue per ad dollar? | Campaign and channel comparison |
| ACOS | spend ÷ revenue | What share of revenue went to ads? | Amazon, marketplace sellers |
| CAC | spend ÷ new customers | What does one customer cost? | Subscriptions, repeat purchase |
The distinction that matters is time horizon. ROAS is a single-transaction measure, so it systematically undervalues advertising for any business where customers come back. If a customer's first order is $50 but they are worth $400 over two years, a 1.5× ROAS on acquisition can be excellent. That is a lifetime value and CAC question, not a ROAS one. Use ROAS to compare campaigns this month; use CAC against LTV to decide how much you can afford to spend at all.
Why your reported ROAS is probably wrong
- Attribution windows. A 7-day and a 30-day window on the same campaign produce very different ROAS. Compare like with like.
- Platform self-reporting. Every ad platform counts conversions it can plausibly claim, so the sum of platform-reported revenue routinely exceeds actual revenue.
- Returns and refunds. Gross revenue includes orders that come back. Apparel with a 30% return rate has a real ROAS a third below the reported one.
- Organic cannibalisation. Branded search ads capture buyers who would have found you anyway, which inflates ROAS without adding sales.
- Ignoring the margin. The most common error, and the one the field above fixes.
A practical habit: track blended ROAS — total revenue divided by total marketing spend — alongside the per-campaign figures. It cannot be inflated by attribution games, because it uses the numbers in your accounts.
What the ROAS figure assumes
ROAS = revenue ÷ ad spend and ACOS = ad spend ÷ revenue × 100, which are reciprocals of each other. "Profit after ad spend" is simply revenue minus spend, and deliberately ignores cost of goods.
- Gross margin is optional. Leave it blank and you get the three classic outputs. Enter it and the calculator adds break-even ROAS (1 ÷ margin), gross profit, net profit after ads, and profit per dollar spent.
- Gross margin means margin on revenue, after cost of goods but before overhead, salaries and platform fees. If you enter a markup instead of a margin the break-even figure will be too optimistic.
- Not modelled: returns and refunds, shipping and fulfilment costs, agency fees, attribution overlap between channels, and repeat purchase value. Each of these makes real ROAS worse than reported ROAS except the last.
- Single-period measure. ROAS says nothing about lifetime value, so subscription and repeat-purchase businesses should judge acquisition on CAC against LTV instead.
Reviewed September 2026.
Sources, checked
- Conversion value per cost: Definition, Google Ads Help. ROAS as conversion value divided by cost.
Figures reviewed . Every worked example on this page is checked against the calculator above.
ROAS Calculator: frequently asked questions
What is a good ROAS?
There is no universal answer, because it depends entirely on your gross margin. Break-even ROAS is 1 ÷ your margin: a 25% margin needs 4×, a 50% margin needs 2×, an 80% margin needs only 1.25×. Anything below your break-even loses money no matter how good it looks.
What's the difference between ROAS and ACOS?
They are reciprocals. ROAS is revenue ÷ ad spend expressed as a ratio, and ACOS is ad spend ÷ revenue expressed as a percentage. A 4× ROAS is a 25% ACOS, and a 2× ROAS is a 50% ACOS.
How do I convert ROAS to ACOS?
Divide 1 by the ROAS and multiply by 100. A 5× ROAS is 1 ÷ 5 = 20% ACOS. Going the other way, divide 100 by the ACOS percentage: a 40% ACOS is a 2.5× ROAS.
What is break-even ROAS?
The ROAS at which gross profit exactly equals ad spend, calculated as 1 ÷ gross margin. At a 40% margin it is 2.5×, so a campaign at 2.5× returns exactly what it cost and anything above that is profit.
What is the difference between ROAS and CAC?
ROAS measures revenue per ad dollar on a single transaction; CAC measures the cost of acquiring one customer. ROAS undervalues advertising for repeat-purchase businesses, where a low first-order ROAS can still be profitable against lifetime value.
Does ROAS include profit?
No, and this is the most common misreading. ROAS uses revenue, so it ignores the cost of goods sold entirely. A campaign at 4× ROAS with a 20% margin loses money on every sale. Enter your gross margin above to see the real figure.
Why is my ROAS different in Google Ads and my analytics?
Attribution windows and models differ, and each platform credits conversions it can plausibly claim. Platform-reported revenue commonly sums to more than the business actually made, so check blended ROAS against your accounts.