At a glance
Avg Replay Duration is a session-replay metric tracked from PostHog data. It measures the average length of the session recordings PostHog captures. Replay length is a quiet proxy for engagement and for how much there is to review: longer replays often mean deeper sessions, while a sudden shift, very short or unusually long, can point to a capture issue or a UX change worth watching on the recordings themselves.
| What it counts | The average duration of captured session replays for the period. |
| Sample type | Backend API data from PostHog session-replay recordings, refreshed on the standard data refresh. |
| Why it matters | Replay length frames how much behaviour each recording holds. Tracking it helps you spot engagement shifts and capture anomalies before you start watching sessions. |
| Reading the value | Compare the current period against the prior period. A sharp change in either direction is worth investigating on the replays. |
| Currency | count |
| Time window | 30D vsP |
| Alert trigger | - |
| Sentiment key | ph_replay_avg_duration |
| 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 Avg Replay Duration for a typical merchant on PostHog. Suppose captured replays average about 2 minutes 40 seconds. After a homepage redesign on 18 May 26, the average jumps to 4 minutes 10 seconds. Longer replays could mean richer engagement or could mean users hunting for something they used to find easily. The card flags the shift; the replays themselves tell the story. Cross-reference Replays Containing Rage Clicks to check whether the longer sessions are frustrated ones. 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_replays_with_rage_clicks | Session Replay sibling: frustrated sessions. |
ph_session_replay_count | Session Replay sibling: how many replays were captured. |
ph_session_replay_coverage | Session Replay sibling: capture coverage. |
pos_avg_session_duration | Engagement sibling: average session length. |
pos_sessions | Audience sibling: total sessions. |
Reconciling against the vendor’s own dashboard
Where to look in PostHog’s own dashboard: In PostHog, open Session Replay. Each recording lists its duration, and the list can be sorted and filtered. The average across the period should align with this card. Note that PostHog can trim or cap recordings, which affects the average. Why the Vortex IQ value may legitimately differ:| Reason | Direction | What to do |
|---|---|---|
| Recording caps. PostHog may cap maximum recording length, truncating long sessions. | Variable | Account for the cap. |
| Sampling. If replay sampling is on, the captured set is a subset of sessions. | Variable | Confirm the sampling rate. |
| Idle handling. How idle time is counted in a recording shifts the average. | Variable | Check the idle settings. |