What this calculator does
This ROAS calculator measures what advertising returns. Enter your ad spend and the turnover attributed to it, and it returns return on ad spend as a multiple, the net return over spend, and ROI as a percentage, along with a table showing how results behave at different spend levels.
ROAS is a media efficiency ratio rather than a profit measure. A 4x return means four pounds of turnover per pound spent, but turnover is not margin. Whether the campaign made money depends on your cost of sales, and the calculator gives you the ratio so you can test it against your own break-even threshold.
When to use it
The routine use is comparing channels and campaigns on a consistent basis, so paid search and paid social can be ranked against each other rather than assessed through separate dashboards with different attribution settings.
The more valuable use is deciding where to stop spending. ROAS declines predictably as budget rises, because the cheapest audiences convert first. Running the calculation across several spend levels shows where incremental return crosses your break-even threshold — the point at which further budget destroys value rather than creating it. That is a much more actionable answer than an average.
Understanding the inputs
Ad spend should include everything required to produce the turnover: media cost plus agency fees, creative production, and tooling. Media cost alone flatters the result, sometimes by 20 percent or more where a retainer is involved.
Revenue must be net of VAT, returns, refunds, and discounts. Ad platforms frequently report gross transaction values including VAT, which inflates ROAS by a full fifth for a UK retailer, so check what your tracking is actually sending. Separating prospecting from retargeting is also worthwhile, since blending them hides whether new customer acquisition is working at all.
How is this calculated?
ROAS = Revenue / Ad Spend. A 5× ROAS means £5 returned for every £1 spent on advertising.
A worked example
A UK retailer spends £8,000 on a campaign and the platform reports £34,000 of revenue. Taken at face value that is 4.25x ROAS with £26,000 of gross return. But the tracking includes VAT, so real turnover is about £28,333 and true ROAS is 3.54x.
Now apply a 42 percent gross margin. That £28,333 produces £11,900 of gross profit, leaving £3,900 after the ad spend — profitable, since break-even ROAS at that margin is about 2.38x. Factor in a 25 percent return rate, though, and effective turnover falls to roughly £21,250, gross profit to £8,925, and profit after spend to £925. Same campaign, three very different verdicts.
Limitations and assumptions
The main weakness is attribution rather than arithmetic. Platform-reported revenue credits the platform for conversions it may only have influenced, and multi-touch journeys make clean attribution genuinely difficult. Two dashboards will routinely claim the same order. Treat reported ROAS as directional and reconcile it against total turnover.
The calculator also ignores gross margin, so it cannot say whether a campaign was profitable — only what turnover it returned per pound. It excludes lifetime value, which can justify a first-order ROAS below break-even, and it says nothing about incrementality, since some of that turnover would have arrived regardless. Read it alongside your margin structure and, where budget allows, a holdout test.
Common Questions
- What counts as a good ROAS?
- It depends entirely on gross margin, so a universal figure misleads. Break-even ROAS is one divided by your margin: a business at 40 percent margin needs 2.5 to break even, one at 20 percent needs 5. The commonly quoted 4x target only makes sense for a particular margin structure.
- Should revenue be measured before or after VAT?
- Before. Ad platforms often report gross transaction values including VAT, which inflates ROAS by 20 percent for a UK retailer. Revenue of £34,000 reported gross is only £28,333 net, turning a 4.25x ROAS into 3.54x. This single adjustment changes the conclusion on a great many campaigns.
- What is the difference between ROAS and ROI?
- ROAS divides revenue by ad spend and ignores cost of sales entirely. ROI measures profit against total cost. A campaign can report 5x ROAS and still lose money once product cost, carriage, and returns are deducted. ROAS is a media efficiency measure rather than a profitability measure.
- Should returns be deducted from campaign revenue?
- Yes, and omitting them is a frequent distortion. Clothing and furniture routinely see 25 to 30 percent return rates, so platform-reported revenue can overstate genuine ROAS by a third. Use revenue net of returns, or at minimum recognise that the dashboard figure is systematically optimistic.
- Why does my platform ROAS exceed what my accounts show?
- Attribution. Platforms credit themselves for conversions they may only have influenced, using different windows and models, and several will claim the same sale. Comparing reported revenue against accounting turnover typically reveals a gap of 20 to 40 percent. Only one of those figures ends up in your statutory accounts.
- Should I measure ROAS on new customers only?
- It is the more honest test. Retargeting existing customers reports very high ROAS while adding little incremental turnover, and blending it with prospecting makes a mediocre acquisition programme look strong. Separating the two usually shows that scale is constrained by the prospecting figure alone.
- How does lifetime value change the target?
- It relaxes it considerably, where repeat purchasing is real. A business whose customers buy four times a year can accept a first-order ROAS below break-even because the relationship is profitable overall. Only do this on cohort evidence — many businesses assume repeat rates that never actually materialise.
- Why does ROAS decline as I spend more?
- Because the cheapest audiences convert first. The most responsive prospects are reached at low cost, and extending further into the market costs more per conversion. Nearly every account has a spend level beyond which incremental ROAS falls below break-even, and locating it matters far more than improving the average.
- What should I optimise instead of ROAS?
- Incremental profit. A campaign at 8x on £3,000 of spend generates less profit than one at 3x on £50,000, provided 3x clears break-even. Managing to the ratio rather than the total keeps many businesses operating well below the scale they could profitably sustain.