You look at ROAS in Meta Ads Manager and it reads 3.5. That number is the revenue Meta attributes to itself, divided by Meta spend. It isn't net profit. The gap with true ROAS can push a campaign that looks profitable below zero once costs are taken out.
The three ROAS every e-commerce merchant should know
1. Platform ROAS (what Meta/Google show you)
This is the ROAS calculated by the ad platform itself:
Platform ROAS = Revenue attributed by the platform / Ad spend on that platform
The problem: each platform attributes conversions according to its own rules. Meta uses a 7-day click and 1-day view window. Google uses 30 days post-click. TikTok uses 7-day click and 1-day view.
Result: if a customer sees a Meta ad, clicks a Google ad, then buys, both platforms claim the sale. Your total revenue is counted twice in the ad reports.
2. Blended ROAS (or MER — Marketing Efficiency Ratio)
Blended ROAS is the most honest metric for judging the overall efficiency of your marketing spend:
Blended ROAS = Total store revenue / Total ad spend (all platforms)
No double counting. No biased attribution. Just the ratio between what you bring in and what you spend on ads. If your blended ROAS is 3, it means that for every euro spent on advertising, your store generates €3 in revenue.
3. True ROAS (the ultimate metric)
True ROAS goes even further by using net profit instead of revenue:
True ROAS = Net Profit / Total ad spend
It's the only metric that tells you how much money you actually make for every euro invested in ads. A blended ROAS of 3 can correspond to a true ROAS of 0.3 if your margins are thin and your operating costs high.
Why platform ROAS lies
Beyond the multiple-attribution problem, here are the other reasons you can't trust the ROAS shown by Meta or Google:
- Browser signal loss: some purchases no longer reach the pixel. Meta fills in with modeling you can't verify line by line. The gap is measured by comparing with Shopify orders; it isn't a universal percentage.
- Returns and cancellations: Meta records a purchase at the time of conversion. If the customer returns the product, the ROAS doesn't change.
- Discounts and promo codes: if you sell a €50 product with a 20% off code, Meta still attributes €50 in revenue.
- Cross-device: a user who clicks an ad on mobile and buys on desktop may or may not be counted as a conversion, depending on Meta's matching.
An example that hurts
Illustrative example, not a customer case. A merchant spends €5,000/month on Meta Ads and €2,000 on Google Ads:
- Meta reports: €20,000 in attributed revenue → Meta ROAS = 4.0
- Google reports: €10,000 in attributed revenue → Google ROAS = 5.0
- Total "attributed" revenue: €30,000
But the store's actual revenue for the month: €22,000. The €8,000 gap comes from double-counted conversions and modeled estimates.
- Blended ROAS = 22,000 / 7,000 = 3.14 (vs 4.0 and 5.0 reported)
- Net profit (after all costs) = €2,500
- True ROAS = 2,500 / 7,000 = 0.36
For every euro spent on ads, this merchant only makes 36 cents of profit. The Meta ROAS of 4 gave a false impression of outstanding performance.
How to calculate your breakeven ROAS
Breakeven ROAS is the minimum ROAS to avoid losing money:
Breakeven ROAS = 1 / Gross Margin %
If your margin before ads (after COGS, shipping and fees) is 40% of revenue, the threshold is 1 / 0.40 = 2.5. This 2.5 is compared with platform ROAS or blended ROAS, that is, revenue divided by ad spend. Below it, the revenue generated no longer covers your pre-ad costs. True ROAS, on the other hand, is already net profit divided by ad spend: it signals a loss only when it drops below 0.
Knowing your breakeven ROAS is essential for setting realistic targets for your campaigns.
How to track your true ROAS every day
Calculating true ROAS by hand is tedious: you need to cross-reference Shopify data (revenue, orders, returns), advertising data (Meta, Google, TikTok spend) and operating costs (COGS, shipping, handling).
ProfitPilotPro shows blended ROAS (revenue / ad spend), true ROAS (net profit / ad spend) and the breakeven threshold, based on Shopify orders and Meta, TikTok and Google spend. The threshold is read next to the revenue / ad spend ROAS. The formulas are in the metrics guide.
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