ROAS tracking

Shopify ROAS tracking

Add Meta's reported ROAS to Google's, and the total usually overstates what your store actually made. The two platforms are frequently crediting themselves for the same order.

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ROAS answers a narrower question than it sounds like

Return on ad spend, as reported inside Meta or Google, is revenue that platform attributed to itself divided by what you spent there. It's a real number, calculated correctly — it just answers “how did this platform's own attribution model score itself,” not “how much of my actual revenue came from this platform.”

Adding platform ROAS together double-counts orders

A customer who saw a Meta ad, then searched and clicked a Google ad, then bought — is a single order that both platforms may independently claim inside their own attribution windows. Sum their reported revenue and you've counted that order twice, sometimes more if email or affiliate tracking also claims a piece of it.

Blended ROAS and MER measure differently

Blended ROAS is the revenue included in the calculation divided by total advertising spend across the selected channels:

Blended ROAS = Revenue ÷ Total advertising spend

The part that trips people up is the numerator. Some businesses use total store revenue, some use only the revenue they attribute to advertising, and some exclude organic or repeat-customer revenue from the calculation entirely. None of these is more “correct” than the others — the actual requirement is picking one definition and keeping it consistent, so the number means the same thing from one month to the next.

MER (marketing efficiency ratio) is commonly calculated as total store revenue divided by total marketing spend, which sidesteps attribution entirely. It's cruder — it can't tell you which channel is working — but it can't be inflated by double-counted attribution either, which makes it a useful sanity check against blended ROAS.

A week of spend, four different numbers

Illustrative example, not a real account:

Meta-reported revenue (spend $4,000)$16,000 (4.0x)

Google-reported revenue (spend $3,000)$13,500 (4.5x)

Naive sum of both platforms' reported revenue$29,500

Estimated overlapping orders (claimed by both)≈ $8,500

Unique Shopify revenue that week, net of refunds$21,000

Blended ROAS ($21,000 ÷ $7,000 combined spend)3.0x

MER (total store revenue ÷ total marketing spend)varies — depends on total store revenue, not shown here

The gap between the platforms' combined claim and unique Shopify revenue isn't fraud on either side — it's overlap, plus whatever refunds happened after the platforms had already logged their numbers. The overlap figure here is an estimate for illustration; the real number depends on how much cross-channel journey overlap your store actually has.

Refunds, discounts, tax and shipping move the real number

Shopify revenue itself isn't a single obvious figure either — gross sales, net sales after discounts and refunds, and revenue including tax and shipping can each tell a different ROAS story from the same order data. We cover how that plays out on the Google Ads tracking page in more detail.

Neither number proves the sale wouldn't have happened anyway

Blended ROAS and MER are both efficiency ratios, not proof of incrementality — a high ratio doesn't confirm that advertising caused the sale rather than a customer who was going to buy regardless. Attribution data, at every level of this page, is a reconstruction based on the evidence available, not a perfect record of cause and effect.

What Attribix shows instead

Attribix combines Meta and Google spend with net Shopify revenue and shows blended ROAS and MER alongside each platform's own reported number — so the gap between them is visible, rather than something you'd only notice by reconciling spreadsheets manually.

Common questions

What is ROAS?

Return on ad spend — revenue attributed to advertising divided by what you spent on it. On its own it's a ratio, not a profit figure.

What is MER?

Marketing efficiency ratio — total store revenue divided by total ad spend across every channel, with no attribution model involved. It moves less than platform ROAS because it doesn't depend on who gets the credit.

What's the difference between MER and ROAS?

ROAS relies on attributing individual orders to individual ads or platforms. MER skips attribution entirely and compares total revenue to total spend, which makes it steadier but less useful for deciding which specific campaign to scale.

Why doesn't my blended ROAS match Meta's or Google's reported ROAS?

Meta and Google each calculate ROAS only from the orders their own attribution model credits to them — and both platforms often claim credit for the same order, so their combined ROAS routinely overstates blended reality.

Is a higher ROAS always better?

Not necessarily. A campaign can show a high ROAS on orders that would likely have happened anyway, while a lower-ROAS campaign might be reaching genuinely new customers. ROAS measures efficiency, not incrementality.

See your blended ROAS

Connect your store and ad accounts to compare platform-reported ROAS against actual Shopify revenue.