You open Meta. It says 4.2. You open Google. It says 6.1. TikTok says 2.0. Then you open Shopify, and the total is lower than the 3 dashboards added together.
Blended ROAS is your total sales divided by your total ad spend across every channel. It uses the money that came in, so no platform can claim the same sale twice.
Blended ROAS = total sales ÷ total ad spend
What the dashboards say vs what came in
An example April, for a shop on 3 channels:
| Source | Spend | Sales it claims | ROAS it reports |
|---|---|---|---|
| Meta Ads Manager | £20,000 | £84,000 | 4.2 |
| Google Ads | £12,000 | £73,200 | 6.1 |
| TikTok Ads | £3,000 | £6,000 | 2.0 |
| Added up | £35,000 | £163,200 | |
| Shopify | £150,000 |
The same month as a picture:
A shopper clicks a Meta ad on Monday, clicks a Google ad on Wednesday and buys on Thursday. Both platforms count the sale. Shopify counts it once. Each platform counts it honestly by its own rules.
Now start from Shopify:
Every £1 on ads came with £4.30 of sales. That £150,000 also includes email, organic search and people who typed your name straight in.
Is 4.3 good?
Check it against your break-even ROAS, the lowest return at which the ads stop losing money. It comes from the costs that rise with every sale: product, shipping and packing, payment fees, returns.
Say you keep 38% of each sale after those. Break-even is 1 ÷ 0.38 = 2.63. Your target, 20 to 30% above, is 3.2 to 3.4. Here is where 4.3 lands:
Well above target, so you can probably spend more and grow. Staff, rent and software stay out of the break-even. Check those in a monthly view instead.
A 4.3 says you have room to spend. The next question is where the extra should go.
Use it to test a budget change
- Add £5,000 to Meta for a month.
- Watch blended ROAS. Ignore Meta’s own figure.
- Say total sales rise £15,000. Blended ROAS reads 4.1 (£165,000 ÷ £40,000) and looks fine, but the extra £5,000 brought £15,000: a 3.0 return, below your 3.2 target.
That gap is incrementality: what the extra spend added, over what you would have sold anyway. Blended ROAS can look fine while the extra money earns far less than the rest of your budget. Try it with last month’s numbers:
Try it
What did the extra spend actually add?
Last month: £150,000 of sales from £35,000 of ads, so a blended ROAS of 4.3. Your break-even is 3.5.
It works in reverse too. Cut a channel and blended ROAS holds? That budget was mostly buying credit for sales you would have made anyway.
Track it in 4 columns
Once a month, fill in:
| Month | Sales (Shopify) | Total ad spend | Blended ROAS |
|---|---|---|---|
| April | £150,000 | £35,000 | 4.3 |
Compare with last month, with your break-even, and with the same month last year to allow for seasons.
Which number for which job
- Blended ROAS: sales ÷ ad spend. Do the ads pay overall?
- MER: sales ÷ all marketing spend, including influencers and affiliates. The same idea, wider.
- Platform ROAS: which campaign, ad or audience to back inside one platform.
Related reading
- Easier Ads Budgeting: how much a new channel needs to spend for a fair test
- Break-even ROAS: the floor your blended ROAS has to beat, with a calculator
- Platform ROAS is a lie: why each dashboard runs high
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Quick answers
What is blended ROAS?
Blended ROAS is your total sales divided by your total ad spend across every paid channel. It uses your real sales from Shopify, so no platform can count the same order twice.
How do you calculate blended ROAS?
Total sales ÷ total ad spend. If you took £150,000 in April and spent £35,000 across Meta, Google and TikTok, your blended ROAS is 4.3.
What is a good blended ROAS?
It depends on your costs. Work out your break-even ROAS from your costs per order, then aim for 20 to 30% above it.
How is blended ROAS different from MER?
Blended ROAS counts ad spend only. MER counts all your marketing spend, such as influencers and affiliates as well as ads. If ads are most of your marketing, the 2 numbers sit close together.
