Configure Session Replay sampling

Configure sampling to control how many sessions Amplitude captures within your organization's quota. Use a manual rate for a fixed capture percentage or dynamic sampling to adjust the rate each day. For capture based on events, properties, or URLs, use Targeted Replay Capture.

Open project sampling settings

1. Go to Settings > Organizational Settings > Session Replay Settings.
2. Select the project you want to configure.
3. In Sampling, set a manual sample rate for the conditions you define, or choose dynamic sampling for the project.

Sampling

View and set the sampling rate for any condition you define. The Sampling section shows a monthly estimate of sessions that match the conditions you define, and estimates how many sessions Amplitude captures. By default, Session Replay uses the Any Session condition. For more information about conditions, refer to Targeted Replay Capture.

Choose a manual rate for your quota

Distribute your capture quota over the month. For example, a quota of 2,500,000 sessions divided by an average of 3,000,000 monthly sessions is about 83%. Set the SDK's sampleRate to .83 or lower to spread capture through the month. For SDK parameter units and defaults, refer to your Session Replay SDK.

Amplitude recommends starting with a low rate, such as .01. If that rate doesn't capture enough replays, increase it over a few days. Use Measure replay capture to monitor captures.

Quota reset and capture limits

• Amplitude stops capturing replays when you reach the monthly session quota.
• Session quotas reset on the first of every month.
• Replays with processing errors don't count toward the monthly quota.
• Replays with a retention error already counted toward quota when the session was within the retention period.

Dynamic sampling

If you're unsure how to balance your sample rate against your monthly quota, dynamic sampling may help. Dynamic sampling adjusts the sample rate each day so you use your full quota by month end. Dynamic sampling helps you stay within your quotas, but Amplitude can't guarantee an exact 100% match or prevent overage. Choose which projects use dynamic sampling. Session Replay quota is org-wide, but the sampling rate is per project. If you enable dynamic sampling on multiple projects, those projects share the same sample rate.

How dynamic sampling sets the rate

Each day, Amplitude estimates your org's projected replay count by month end using analytics session counts across all projects with session capture enabled. For projects with a manual sample rate, Amplitude multiplies that rate by the project's session count to estimate each project's quota consumption. It then allocates the remaining quota to dynamic-sampling projects and sets their rates accordingly.

Because the estimate relies on analytics session counts rather than actual replay captures, discrepancies between the two can affect the result. For example, a project with a large analytics session count and a 100% manual sample rate may appear to consume most or all of the monthly quota, even if it isn't actively capturing replays. In this case, dynamic-sampling projects may receive a 0% rate early in the month.

To improve the accuracy of dynamic sampling:

• Configure the sample rate in Session Replay settings for every project with session capture enabled. Dynamic sampling doesn't account for rates set only in the SDK, and projects with no rate configured in settings disable dynamic sampling for the entire org.
• For projects that aren't capturing replays, set the sample rate to 0% or disable session capture so their session counts don't inflate the org-wide estimate.
• Dynamic sampling works best when all projects in your org use it. You can mix dynamic and manual rates, but the estimate is less accurate when analytics session counts don't match actual replay captures.

Session Replay doesn't support dynamic sampling if any project in the org uses targeted session replay capture.