You run campaigns on Google Ads and Meta Ads. Google claims 100 conversions. Meta claims 80. You only had 70 actual sales. What's going on? This guide explains exactly why the numbers differ and what to do about it.
Fundamental Differences
Attribution Windows
The time window for claiming conversion credit differs significantly:
| Platform | Click Attribution | View Attribution |
|---|---|---|
| Google Ads | 30 days (default) | 1 day (default) |
| Meta Ads (post-iOS14) | 7 days | 1 day |
A conversion that happens 10 days after clicking a Meta ad won't show in Meta's attribution, but will in Google's.
View-Through Attribution
Platforms count "view-through" conversions differently:
- Meta: Counts if someone saw ad, then converted (even without clicking)
- Google: More conservative view-through counting
- Impact: Meta historically claimed more view-through conversions
Cross-Device Tracking
- Meta: Logged-in users tracked across devices
- Google: Logged-in users plus modeled cross-device
- Impact: Different abilities to connect user journeys
iOS14 Impact on Meta
Apple's App Tracking Transparency dramatically changed Meta's tracking:
Before iOS14
- Full pixel tracking on iOS devices
- 28-day click, 7-day view attribution
- Granular conversion data
After iOS14
- Many iOS users opted out of tracking
- Attribution windows shortened
- Modeled conversions fill gaps
- Delayed reporting (up to 72 hours)
This means Meta's reported conversions are increasingly modeled estimates, while Google (less affected by iOS changes) maintains more direct measurement.
Conversion Counting Methods
One Per Click vs All
- One per click: Only one conversion per ad click
- All: Every conversion from each click
- Impact: "All" counting inflates numbers for repeat purchases
Different Conversion Events
Even "purchase" can mean different things:
- When the conversion fires (checkout complete vs thank you page)
- Deduplication logic
- Value attribution
Why Both Platforms Claim Credit
Imagine this customer journey:
- Monday: Sees Meta ad, clicks, browses
- Wednesday: Googles your brand, clicks Google ad
- Friday: Returns directly, purchases
Meta says: "That's our conversion! User clicked our ad Monday."
Google says: "That's our conversion! User clicked our ad Wednesday."
Reality: One sale, two platforms claiming credit.
Practical Reconciliation
Accept Discrepancy
10-30% discrepancy between platforms is normal. Don't try to make numbers match exactly - it's impossible.
Use Platform Data for Platform Optimization
- Optimize Google Ads using Google's data
- Optimize Meta Ads using Meta's data
- Each platform's data is internally consistent
Use Unified Source for Strategic Decisions
- Use GA4 or a unified analytics tool for cross-channel decisions
- This is your "source of truth" for budget allocation
- Accept that this will differ from platform totals
Align What You Can
- Use similar attribution windows where possible
- Match conversion event definitions
- Compare same time periods
How Xplainr Helps
Xplainr normalizes data from Google Ads and Meta Ads into a unified view with consistent metrics. Instead of reconciling spreadsheets, you see all channels together with clear labels on what each source reports - making cross-channel decisions simpler.
Try the Unified Dashboard
Connect all platforms in one view
Explaining to Stakeholders
When stakeholders ask why numbers don't match:
Short Version
"Each platform uses different methods to claim credit for conversions. They both report accurately by their own rules, but the rules are different. We use [unified source] for cross-channel decisions."
Longer Version
Explain attribution windows, view-through differences, and why overlap is normal. Emphasize that you're optimizing each platform with its own data while using a unified view for strategic allocation.
Related Resources
- Create a Single Source of Truth
Solve platform discrepancies with a unified data approach.
- Cookieless Attribution
Navigate attribution as tracking capabilities decline.