Workspaces with the newer activity features use this single rule everywhere it applies. Some older screens (the Staff view's minutes column, the public API's leaderboard, timesheets and goals) still use their own copy, which can differ slightly (see the end of this article).
The rule
For one person in one period:
Take each session that has ended.
Its length is the end time minus the start time.
If idle time tracking is on, subtract that session's idle time. The result never goes below zero.
A session that has not ended yet counts for nothing (it counts when it ends).
Add all manual adjustments (awards add minutes, removals take them away).
Round once, at the end.
The result is the number shown as Minutes.
Periods
This period: everything since the last reset.
Last period: the saved history of the period before.
All time: history plus the current period.
Where the newer rule is used
The leaderboard, including its This period / Last period / All time choice.
The My Quotas widget on Home.
The Activity breakdown tab on a profile (see "See exactly where someone's minutes came from (activity breakdown)").
Where older numbers may differ slightly
The Staff view's minutes column, the public API's leaderboard and activity endpoints, timesheets, and goals still have their own calculation. They can differ in small ways: whether idle time can take a session below zero, how rounding is done, and whether adjustments are included. If two screens differ by a minute or two, that is why.
Related articles
Add or remove minutes by hand (manual adjustments)