If you run Meta Ads for a DTC brand and check both your Meta Ads Manager and your Shopify or GA4 dashboard, you've probably noticed they don't agree. Meta says you had 80 purchases. Shopify says 45. Someone is wrong, and you're not sure who to trust.
Neither number is wrong. They're just measuring different things. Understanding the difference is one of the most important things you can do for your paid media decision-making.
The two numbers you're looking at
Platform-reported ROAS
What Meta Ads Manager shows you. It counts a purchase as a conversion if someone clicked or viewed your ad within the attribution window — even if they also clicked a Google ad, opened an email, or visited the site organically before buying.
Blended ROAS
Total revenue ÷ total ad spend across all channels. This is what you actually made per pound/dollar of ads — it doesn't care which platform takes credit. It's the only number that tells you if paid media is profitable overall.
The gap between the two is caused primarily by attribution overlap — multiple ad platforms claiming credit for the same purchase, and the attribution window counting people who would have bought anyway.
Why the attribution window matters so much
Meta's default attribution window is 7-day click, 1-day view. This means if someone sees your ad and then buys within 7 days of clicking it (or 1 day of just viewing it), Meta counts that as a purchase from your ads — regardless of what else happened in between.
For some product categories this is reasonably accurate. For others — especially higher-consideration purchases — a customer might click your ad, browse for a week, read reviews, click a Google ad, and then come back directly to buy. Meta, Google, and email all claim that sale. Your Shopify dashboard counts it once. The platforms collectively count it three times.
The practical result: Platform-reported ROAS almost always overstates actual returns for DTC brands running across multiple channels. Blended ROAS almost always understates the contribution of any single channel. Neither tells the full story alone.
The three numbers every DTC brand should track
Rather than trying to reconcile platform numbers with Shopify numbers (a task with no clean answer), track these three in parallel:
- Platform-reported ROAS — for relative performance comparison within Meta. Use this to decide which campaigns, ad sets, and creatives are winning against each other. Don't use it to judge profitability.
- Blended ROAS — total revenue ÷ total ad spend across all paid channels. Use this to judge whether paid media is profitable overall. If this number drops, something is wrong regardless of what any individual platform is reporting.
- MER (Marketing Efficiency Ratio) — total revenue ÷ total marketing spend (including organic, influencer, email, everything). This is the cleanest high-level signal of marketing health, because it captures halo effects that pure ROAS misses.
What iOS 14.5 changed — and what it means now
Since Apple's iOS 14.5 update introduced App Tracking Transparency, a significant share of iPhone users have opted out of cross-app tracking. This means Meta can no longer see what those users do after leaving its platform — so it can't attribute purchases to those users via the standard Pixel.
Meta's response was Aggregated Event Measurement (AEM), which reports modelled data for opted-out users using statistical inference. This is why you'll sometimes see decimal purchase numbers in Ads Manager — Meta is estimating partial conversions.
The practical implication: if your customer base skews toward iPhone users (which most UK and US DTC audiences do), your Meta-reported purchase numbers are increasingly modelled rather than observed. The direction of the signal is still useful. The absolute numbers are less reliable than they were pre-2021.
How to use this in practice
Stop trying to make the numbers match. Instead, set clear rules for what each number is used for:
- Use platform-reported ROAS for in-platform decisions — which creative wins, which audience to scale, which campaign objective to use
- Use blended ROAS for weekly and monthly profitability reviews
- Use MER for quarterly strategic decisions — whether to increase paid spend overall
- If you're running incrementality tests (Meta's own lift tests, or third-party MMM tools), use those results to calibrate how much of your blended ROAS is actually attributable to paid media
The simplest version: If blended ROAS is healthy and trending up, paid media is working. If it's declining while platform ROAS looks fine, you have an attribution problem or a budget allocation problem — not a creative problem.
Not sure what your numbers are actually saying?
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