Blended ROAS vs. platform ROAS: which number should you trust?
Meta and Google each claim credit for your sales, and together they often claim more than you sold. Here is how to use both numbers without fooling yourself.
Open Meta Ads Manager, then Google Ads, and add up the revenue each one says it drove. Then open Shopify. If the platforms’ total is higher than what your store actually took in, nothing is broken. That is how attribution works.
Each platform counts the sales it touched. A customer who saw an Instagram ad on Monday and clicked a Google search ad on Thursday can be counted by both. Neither is lying. They are just not counting the same thing as your bank account.
Two numbers, two jobs
Platform ROAS is the revenue a platform attributes to its own ads, divided by what you spent there. It is good for comparing campaigns inside one platform. Is the prospecting campaign doing better than the retargeting one? Platform ROAS will tell you.
Blended ROAS is your total store revenue divided by your total ad spend, across every channel. Some teams call it MER, marketing efficiency ratio. It is good for one question only, but it is the important one: is the advertising, taken together, paying for itself?
| Question | Use |
|---|---|
| Which Meta campaign should get more budget? | Platform ROAS |
| Is our total ad spend still profitable? | Blended ROAS |
| Should we spend more next month? | Blended ROAS against break-even |
| Did the new creative beat the old one? | Platform ROAS, same platform |
Compare blended ROAS with your break-even
On its own, a blended ROAS of 3 means little. Against your break-even ROAS it means a lot. If you keep half of every euro of revenue before marketing, your break-even is 2.0, and a blended ROAS of 3 leaves room to grow. If you keep a third, break-even is 3.0 and you are standing still.
Platform ROAS ranks your campaigns. Blended ROAS tells you if you can afford them.
A weekly check that takes five minutes
- Write down total revenue and total ad spend for the last seven days.
- Divide them. That is your blended ROAS.
- Compare it with last week and with your break-even.
- Only then open the platforms, and use platform ROAS to decide where to move money.
The order matters. Start in the platforms and you will spend the morning optimising campaigns while the total quietly drifts below break-even.