Sleep Calculator

Plan bedtime or wake time from your chosen sleep duration and time to fall asleep.

Solve for
hours
min

Go to bed at

22:45

  • Day relative to entered timePrevious day
  • Planned sleep8 hours

How this was calculated

Time in bed = planned sleep duration + time to fall asleep.

This is a schedule planner. It does not predict sleep cycles or determine how much sleep you personally need. Clock arithmetic ignores daylight-saving transitions.

Method

Add the planned sleep duration and time to fall asleep to get total time in bed. Subtract it from wake time to find bedtime, or add it to bedtime to find wake time.

Worked example

To wake at 07:00 after eight hours asleep and 15 minutes falling asleep, go to bed at 22:45 on the previous day.

Assumptions and limits

This is clock arithmetic, not a medical sleep recommendation or a sleep-stage prediction. You choose the duration. It does not assume everyone has fixed 90-minute cycles, and it ignores date-specific clock changes.

Last updated . Results are estimates for informational purposes only.