Understanding Day Calculation in Kapa.ai Retention Reports

Vineet V. · 2025-04-22 11:43:07.642366+00

- In retention reports, if I select each day, how is a day calculated? Does it take UTC or the date settings that we set in our project?

In Mixpanel's retention reports, when you select "each day," the day calculation is based on your project's timezone settings, not UTC by default.According to the documentation, Mixpanel records all events in Coordinated Universal Time (UTC) at intake, but then uses your project timezone setting to output results in reports. For projects created before January 1, 2023, Mixpanel actually converts event timestamps to your project timezone before writing the event to your data stores, meaning timestamps are stored based on the project timezone setting at the time of ingestion. For newer projects, the data is stored in UTC and converted to your project timezone only when displaying results.When you're looking at retention reports with daily intervals, the time buckets will align with days as defined by your project timezone setting. This means that if your project is set to Pacific Time, then "Day 1" would be calculated based on the Pacific Time calendar day, not UTC.You can manage your project timezone under Project Settings, where Mixpanel sets timezones by city or region. If a city or region observes Daylight Savings Time, the offset adjusts appropriately.Managing Timezones for ProjectsIt's also worth noting that Mixpanel offers two different retention modes: 1. Rolling interval retention (default) - Considers time intervals based on user's time of birth (e.g., Day 1 retention = 24-48 hrs since person's birth) 2. Calendar interval retention (advanced) - Considers time intervals based on calendar time (e.g., Day 1 retention = next calendar day since person's birth)You can switch between these modes in the advanced menu under Retention Criteria.Calendar Retention Mode

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