Sleep Midpoint Calculator

How it is calculated

Enter bedtime and wake time as 24-hour HH:MM. The tool converts both to minutes after midnight and finds the sleep length as duration = (wake − bed) mod 1440, so a wake time earlier on the clock than bedtime is taken as the next morning. The midpoint is bed + duration / 2, wrapped around midnight and rounded to the nearest whole minute, then shown as a clock time. The length is shown as hours and minutes.

Some inputs give no result: equal bedtime and wake time (0 hours and 24 hours cannot be told apart), a sleep longer than 20 hours (treated as a typo, for example swapped times), hours above 23, minutes above 59, and times written with AM/PM or seconds. The tool assumes you slept once in one stretch.

Common mistakes

• Typing 12-hour times such as 11:30 PM. The tool needs 24-hour HH:MM (23:30), and 24:00 is not valid, so write 00:00.
• Swapping bedtime and wake time. Bedtime 06:45 and wake 23:30 would mean 16 h 45 min of sleep, and a swap such as 07:05 and 06:45 means 23 h 40 min, which is over the 20-hour limit and shows no result.
• Using the midpoint of a nap or of a single night to judge your chronotype. The measure is meant to be compared over many days, such as workdays against free days.
• Entering the time you wanted to sleep rather than the time you actually fell asleep. Time spent in bed awake moves the midpoint and inflates the duration.
• Giving the same time for bedtime and wake time to mean a full night. That returns no result; enter times that differ by at least one minute.