How ROAS is calculated
ROAS (return on ad spend) is the revenue your ads brought in divided by what you paid for them.
ROAS % = ad revenue ÷ ad spend × 100
Ad cost % of revenue = ad spend ÷ ad revenue = 1 ÷ ROAS
The same number gets written three ways. $4 of revenue for every $1 of spend is 4x, 4:1 or 400%. Google Ads uses the percentage form for Target ROAS bidding: its own example is "$5 USD in sales ÷ $1 USD in ad spend x 100% = 500% target ROAS"1. Many dashboards show the multiple instead. Flip it over and you get ad cost as a share of revenue, which Amazon sellers call ACoS: 4x ROAS means ads cost 25% of the revenue they bring in.
Worked examples
Two campaigns for a store whose contribution margin is 35%: after product, shipping, card fees and refunds, 35 cents of every revenue dollar are left to pay for ads and overheads.
| Campaign A | Campaign B | |
|---|---|---|
| Ad revenue | $5,000.00 | $3,000.00 |
| Ad spend | $1,250.00 | $1,250.00 |
| ROAS | 4.00x (400%) | 2.40x (240%) |
| Ad cost % of revenue | 25.0% | 41.7% |
| Contribution (revenue × 35%) | $1,750.00 | $1,050.00 |
| Profit after ad spend | $500.00 | -$200.00 |
Break-even at a 35% margin is 1 ÷ 0.35 = 2.86x. Campaign A clears it and keeps $500.00. Campaign B's 2.40x sounds respectable, but it loses $200.00: to cover $1,250 of spend at this margin it needed $3,571.43 of revenue. Same product, same margin; the only difference is whether ROAS is above or below break-even.
Is your ROAS good? Compare it with break-even
A ROAS figure on its own doesn't say whether you're making money. "4x is good" is a rule of thumb that's right for some margins and badly wrong for others. The useful comparison is with your break-even ROAS, which is 1 ÷ contribution margin. Above it, the ads make money on the first order. Below it, each ad-driven order loses money, unless you're deliberately paying for customers you expect to buy again.
The table converts between the ways ROAS is written, and shows the contribution margin at which each ROAS exactly breaks even. Read it both ways: at 2.5x, ads cost 40% of revenue, so you need a contribution margin above 40% to profit.
| ROAS | ROAS % | Ad cost % of revenue | Breaks even at a margin of |
|---|---|---|---|
| 1.0x | 100% | 100.0% | 100.0% |
| 1.5x | 150% | 66.7% | 66.7% |
| 2.0x | 200% | 50.0% | 50.0% |
| 2.5x | 250% | 40.0% | 40.0% |
| 3.0x | 300% | 33.3% | 33.3% |
| 4.0x | 400% | 25.0% | 25.0% |
| 5.0x | 500% | 20.0% | 20.0% |
| 6.0x | 600% | 16.7% | 16.7% |
| 8.0x | 800% | 12.5% | 12.5% |
| 10.0x | 1,000% | 10.0% | 10.0% |
To go the other way, from your margin to the ROAS you need, use the break-even ROAS calculator. It has a lookup table for margins from 10% to 80% and explains which margin to use.
Target ROAS: working back from a revenue goal
The helper under the calculator turns a revenue goal and a target ROAS into a budget: max spend = revenue goal ÷ target ROAS. To bring in $20,000 at 4x, you can spend up to $5,000. Spend more and the target slips.
Pick the target from your margin, not from a benchmark. A target equal to your break-even ROAS buys sales at zero profit. Set it above break-even by the profit you want to keep: at a 40% contribution margin, break-even is 2.5x, and a 4x target leaves 15% of revenue as profit after ads (40% margin minus 25% ad cost). Google's Target ROAS bidding works from the conversion values you send it1, so check that your Shopify conversion values match the revenue you use here.
What ROAS doesn't tell you
- Attribution is an estimate. Each ad platform counts the revenue it thinks it caused, and platforms can claim the same order. Adding up ROAS across Meta, Google and TikTok usually overstates what the ads earned. Store-wide revenue ÷ total ad spend (often called MER) is a useful cross-check.
- Where orders come from. Shopify records orders from some AI assistants as a separate sales channel and others as a referral to your online store, which changes what ends up in "ad revenue" in your reports. The guide to Shopify's channel attribution for AI orders covers which is which.
- Revenue isn't profit. ROAS uses revenue before refunds, product cost and fees. That's why the margin input matters.
- First order only. ROAS counts the purchase the ad produced, not repeat purchases. A store with strong repeat business can run below break-even on first orders on purpose, as long as it knows its repeat rate.
- Fixed costs. Clearing break-even means the ads paid for themselves. Your subscription, apps and salaries still need covering from the profit after ads.
FAQ
How do you calculate ROAS?
Divide the revenue from your ads by what you spent on them. $5,000 of revenue from $1,250 of spend is 5,000 ÷ 1,250 = 4, written 4x, 4:1 or 400%.
Is a 2.5 ROAS good?
It breaks even at a 40% contribution margin, because ads then cost 40% of revenue. With a margin above 40% it's profitable; below 40% each ad-driven order loses money.
What ROAS is 25% ACoS?
4x. ACoS is ad spend ÷ revenue, the inverse of ROAS: 1 ÷ 0.25 = 4.
What does 4:1 ROAS mean?
$4 of revenue for every $1 of ad spend, also written 4x or 400%. Whether it makes money depends on your margin: at a 25% contribution margin it only breaks even.
Is ROAS the same as ROI?
No. ROAS uses revenue; ROI uses profit. Campaign A above has a 4x ROAS but an ROI on ad spend of 40%: $500.00 profit after ads on $1,250 spent.
Should I include shipping I charge in ad revenue?
Only if your margin treats it as revenue too. The cleanest setup is product revenue in, and a contribution margin that already nets off what shipping costs you.