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PostHog Numbers Different From Google Analytics

Workaround available Web Updated October 21, 2026

Quick answer

PostHog and GA4 count visitors differently: ad blockers block GA more often, PostHog can merge one person across devices, bot filtering differs, and sessions end after 30 minutes of inactivity. Small gaps are normal; large ones mean one tool is blocked.

Most likely fix: Put both tools on equal footing.

Symptoms

Unique visitors, pageviews or sessions differ noticeably between PostHog, GA4, Plausible or Cloudflare.

Why it happens

  • Ad blockers blocking one tool more than the other
  • Cross-device identification merging users in PostHog
  • Different bot filtering (PostHog blocks known bots by default)
  • Different session timeout definitions
  • Referrers stripped, inflating direct traffic

How to fix it

Try these in order — the most common fix is first.

  1. 1. Put both tools on equal footing

    1. Set up a reverse proxy for PostHog so blocked visitors are counted
    2. Compare the same date range, timezone and page filters

  2. 2. Align session and bot settings

    1. Adjust session_idle_timeout_seconds if your other tool uses a different timeout
    2. Use custom_blocked_useragents to exclude extra bots, or opt_out_useragent_filter to include them

  3. 3. Fix attribution gaps

    1. Add UTM parameters to shared links
    2. Set up cross-domain tracking for traffic between your own domains
    3. Enable the GeoIP transformation in Data pipelines if the world map is empty

This guide also covers

  • posthog vs google analytics numbers
  • posthog different from ga4
  • posthog visitors wrong
  • posthog direct traffic high

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