Your recorded fasting time is based on when you actually started and stopped — not the planned duration.
Common reasons for differences:
You stopped the fast early
You started from "last meal" using a past time
You're viewing an in-progress fast (time updates as you fast)
If you set a 16-hour fast but stopped after 14 hours, KAI records 14 hours as the actual duration.
Note: KAI doesn't currently adjust for time zone changes. If you travel during a fast, the recorded duration may be slightly different from the actual time elapsed.