At a glance
Session Replay Coverage % is a session-replay gauge tracked from PostHog data. It is the ratio of replays captured to sessions observed, the single number that tells you how much of your real user behaviour you can actually watch. High coverage means almost every session is reviewable; low coverage means sampling is too aggressive or capture is broken, and any conclusions you draw from replays risk being unrepresentative.
| What it counts | Replays captured divided by sessions observed, expressed as a percentage. |
| Sample type | Backend API data from PostHog session and replay counts, refreshed on the standard data refresh. |
| Why it matters | Coverage decides how trustworthy your qualitative analysis is. Below 80%, you are watching a thinning sample of behaviour and may miss the sessions that matter. |
| Reading the value | Read the gauge band. Below 80% signals under-capture; check sampling settings and recent deploys. |
| Currency | percent |
| Time window | 30D vsP |
| Alert trigger | <80% |
| Sentiment key | ph_session_replay_coverage |
| Roles | owner, marketing |
Calculation
Calculated automatically from your PostHog data. See the At a glance summary above for what the metric tracks and the worked example below for a typical reading.Worked example
A representative reading of Session Replay Coverage % for a typical merchant on PostHog. Suppose coverage sits at 94%: of roughly 40,000 weekly sessions, about 37,600 are recorded. After a config change on 16 Jun 26 lowers the sampling rate, coverage falls to 55%, below the 80% alert. Now nearly half of all sessions are invisible, so any replay-based conclusion is drawn from a partial, possibly biased sample. Cross-reference Session Replays Captured for the raw count and Sessions for the denominator. For deeper investigation, use Vortex Mind to trace upstream causes; for natural-language exploration, ask Ask Viq.Sibling cards merchants should reference together
| Card | Why merchants reach for it |
|---|---|
ph_session_replay_count | Session Replay sibling: the raw replay count. |
ph_replay_avg_duration | Session Replay sibling: average replay length. |
ph_replays_with_rage_clicks | Session Replay sibling: frustrated sessions. |
pos_sessions | Audience sibling: total sessions, the denominator. |
ph_health_score | Executive sibling: overall tracking health. |
Reconciling against the vendor’s own dashboard
Where to look in PostHog’s own dashboard: PostHog does not show this ratio directly, so reconcile from its parts: read the replay count in Session Replay and the session count in a sessions insight for the same period, then divide. The result should align with the gauge. Your configured replay sampling rate sets the ceiling on coverage. Why the Vortex IQ value may legitimately differ:| Reason | Direction | What to do |
|---|---|---|
| Sampling ceiling. A sampling rate of, say, 50% caps coverage near that level by design. | Variable | Compare coverage to the sampling rate. |
| Session definition. How sessions are counted affects the denominator. | Variable | Match the session definition. |
| Minimum duration. Very short sessions are not recorded, lowering coverage. | Variable | Account for the duration rule. |