Short answer: Google Play install conversions count downloads and include Android reinstalls, while an MMP counts first opens once per source. Every counting, a 30-day default window and interaction-day reporting widen the gap. Compare against your MMP's first_open conversion instead.
Why Google's install count runs higher
Install vs first open: Google Play conversions are recorded when the app is downloaded, while third-party tools record installs when the app is first opened.
Google's developer documentation says Play data measures app installs, whereas third-party data measures first opens. Not everyone who downloads opens the app, so Google's figure is higher by design.
Which Google conversion action should I compare?
Compare against the first_open conversion your MMP sends to Google, not the Google Play install conversion. That puts both tools on the same definition of an install.
Likely causes
- Downloads compared with first opens. Play conversions count downloads; MMPs count first opens.
- Reinstalls. Google says Google Ads counts Android reinstalls by people who uninstalled as install conversions. Many MMPs only count a reinstall as new after a re-attribution window. See reinstalls inflating installs.
- Every vs One counting. Google says actions that count Every record more than third parties that count One.
- Window length. Google tracks first opens or installs within 30 days of the ad interaction by default.
- Date basis. Google reports conversions on the day of the ad interaction in the account's time zone.
How to confirm it
- Open the conversion action and check its source: Google Play or your MMP.
- Read the Count setting: Every or One.
- Add the Conversions (by conv. time) column so Google reports on the day the install happened.
- Check the Google Ads account time zone against your MMP's.
- Compare your MMP's Google lookback window with Google's install window.
How to fix it
- Use your MMP's first_open conversion for comparisons and, where it fits your strategy, for bidding.
- Set install conversions to count One.
- Compare on conversion time and the same time zone.
- Align windows, or record the expected gap so the team stops chasing it.
- Treat Play download counts as a separate store metric.
| Difference | Google Ads | Typical MMP |
|---|---|---|
| Install definition | Download (Play) | First open |
| Reinstalls | Counted on Android | After a re-attribution window |
| Default install window | 30 days | Set per MMP |
| Report date | Ad interaction day | Usually install day |
Google also says some invalid conversions are removed later, so its totals can drop after the fact. The Google installs troubleshooter walks through the checks, and which number to trust covers how to use both figures.