- ROAS (Return on Ad Spend) measures the gross performance of your ad: revenue divided by ad spend. It tells you whether the advertising platform is working, but it ignores your operating costs entirely.
- ROI (Return on Investment) is your final financial return. It accounts for what it costs you to produce, package and ship the product. A campaign can post a healthy 3× ROAS and still deliver a negative ROI if your margins are thin.
| ROAS | ROI | |
|---|---|---|
| Question it answers | Are my ads working? | Is my business making money? |
| Includes product cost | No | Yes |
| Expressed as | A multiple (3.6×) | A percentage (+59.3%) |
| Who watches it | Media buyers | Owners and finance |
| Break-even point | Depends on your margin | Always 0% |
The same campaign, two verdicts
Take a campaign that spent 1,000 and generated 3,000 in revenue. The ROAS is a comfortable 3×, and in most agency reports that is where the slide ends.
Now add the cost of goods. If those products cost you 2,500 to make and ship, your net profit is 3,000 − 1,000 − 2,500 = −500. Your ROI is −14.3%. Same campaign, same 3× ROAS, and the business lost money on every order it celebrated.
Flip the margins and the verdict flips with them. If the same 3,000 of revenue only cost you 600 to deliver, net profit is 1,400 and ROI is +87.5%. Nothing about the advertising changed — only what sits behind it.
So which one should you optimise for?
Both, at different altitudes. Media buyers optimise ROAS because it is the number the platform can actually move: creative, targeting and bidding all push on it, and it updates fast enough to act on. Owners watch ROI because it is the number the bank account reflects.
The bridge between the two is break-even ROAS. It translates your margin into a ROAS target, so the media buyer can keep working in the metric they control while still protecting profit. Give a buyer a target of "beat 2.5×" and they know what to do; give them "improve ROI" and they do not.
Where ACOS fits
ACOS (Advertising Cost of Sale) is simply ROAS turned upside down and written as a percentage: ad spend divided by revenue. A 4× ROAS is a 25% ACOS; a 2× ROAS is 50%. Amazon sellers work in ACOS, Meta and Google advertisers work in ROAS, and the calculator shows both so you never have to convert by hand in a meeting.
A word on attribution
Neither metric is better than the revenue figure you feed it. Ad platforms are graded on their own homework: Meta and TikTok will both happily claim the same sale, and the sum of platform-reported revenue routinely exceeds what the store actually took. Before you trust a ROAS to two decimal places, check the total against your real store revenue for the same period, and scale accordingly.