If you have ever added up the conversions reported by Meta Ads, Google Ads, TikTok, and LinkedIn for the same month and compared it to your Shopify order count, you have noticed the problem. The platform totals exceed your actual sales, often by a significant margin. This is not a glitch, a billing error, or a sign that any platform is lying to you. It is the predictable result of how independent attribution systems work.
The Core Problem: Multiple Platforms, One Customer
Here is a realistic customer journey:
- Monday: Customer sees a Meta awareness ad while browsing Instagram (Meta’s 7-day view window starts)
- Wednesday: Customer clicks a Google Shopping ad while searching for the product (Google’s 30-day click window starts)
- Thursday: Customer receives an email from your Klaviyo flow, clicks through, and purchases
Result: Meta claims the purchase (view-through, within 7 days). Google claims the purchase (click-through, within 30 days). Klaviyo claims the purchase (email click, last touch). Your email platform claims it too. Shopify shows 1 order. Three platforms are each crediting themselves for one sale.
This is called attribution overlap, and it is the single biggest source of confusion in multi-channel advertising measurement.
Why Each Platform Uses Its Own Attribution
Each ad platform runs its own attribution system because:
- They can only see their own touchpoints, not your full customer journey
- Each platform has a commercial incentive to show as much value as possible
- There is no shared industry standard for cross-platform attribution
When Meta says “we drove 200 purchases,” it means “200 people who purchased also had a Meta ad touchpoint within our attribution window.” Not: “these 200 purchases would not have happened without Meta.”
How to Read Each Platform’s Numbers Correctly
Meta Ads Manager
Default: 7-day click, 1-day view attribution. Reliable for comparing performance within Meta (which campaign, audience, ad). Not reliable for comparing Meta ROAS against Google ROAS directly.
Google Ads
Uses data-driven attribution (DDA) by default for qualifying accounts, or last-click otherwise. Google Ads Manager pulls data from GA4 or its own conversion tracking. More trustworthy for lower-funnel conversions (shopping, brand search) because users are actively searching with intent.
TikTok Ads Manager
Default: 7-day click, 1-day view. View-through attribution on TikTok is especially prone to overclaiming because users watch content passively and may have no purchase intent when they see the ad.
LinkedIn Campaign Manager
Default: 30-day click, 7-day view. The 7-day view window is much wider than other platforms, which means LinkedIn routinely reports more conversions than it actually drove on a last-click basis.
The Three-Layer Measurement Framework
Layer 1: Shopify as ground truth
Shopify’s total revenue and order count is the only unbiased number. Everything else is attribution of that revenue across channels.
Layer 2: GA4 last-click for cross-channel comparison
With UTM parameters on all your campaign URLs, GA4 shows you which channel received the last click before conversion. This is not perfect, but it is consistent across platforms. When Meta’s last-click GA4 revenue is $15k and Google’s is $40k, that tells you something useful about where users are actually clicking to purchase — even if upper-funnel channels contributed to awareness.
Layer 3: Platform-native attribution for within-platform optimisation
Use each platform’s own attribution data for decisions within that platform: which campaign performs better, which audience to scale, which creative drives conversions. Do not compare Meta’s native attribution to Google’s native attribution when deciding budget allocation.
A Practical Heuristic: Sum Your Platform Revenue vs Shopify Revenue
Add up the revenue reported by all your ad platforms in a given month. Divide Shopify revenue by that sum. If your ratio is 0.6, your platforms are collectively overclaiming by 40%. A ratio of 0.3–0.5 is common for stores running multiple platforms with broad attribution windows.
This ratio helps you calibrate how much weight to put on any single platform’s reported numbers. When Meta reports $50k revenue and your ratio is 0.4, you might expect Meta’s actual contribution (if you could perfectly measure it) to be around $20k.
What to Do About It
- Tag everything with UTMs so GA4 can attribute consistently across platforms
- Choose consistent attribution windows when comparing platforms (change both to 7-day click, 1-day view if possible)
- Use Shopify as your revenue ground truth, not platform totals
- Run incrementality tests when you want to know if a specific channel is truly driving incremental revenue
Book your free Shopify tracking audit here and we will help you set up a measurement framework that gives you reliable cross-channel data rather than confusing platform-inflated numbers.