Sleep Calculator - Free Online Tool
Plan a bedtime from wake time and sleep goal.
About this tool
Work backward from a wake-up time to find a suggested bedtime using a sleep-duration goal and the minutes you expect to take to fall asleep. The result is a clock-time planning estimate that can fall on the previous calendar day.
How it works
- Enter the intended wake-up time using the 24-hour clock.
- Enter desired time asleep in hours and an estimate of minutes to fall asleep.
- Read the suggested bedtime and whether it falls on the day before the wake-up.
Example use cases
- Plan for a 07:00 wake-up: For 8 hours of desired sleep and 20 minutes to fall asleep, allow 8 hours 20 minutes in bed. The suggested bedtime is 22:40 on the previous day.
- Different fall-asleep estimate: With a 06:30 wake-up, 7.5 hours desired asleep, and a 15-minute settling buffer, the calculated bedtime is 22:45 on the previous day.
Frequently asked questions
Does this predict when I will actually fall asleep?
No. It uses the number of minutes you enter as a planning buffer. Actual time to fall asleep and sleep continuity can vary.
Does the calculator use sleep cycles?
No. It subtracts the entered sleep goal and fall-asleep time from your wake-up time. It does not forecast sleep stages or guarantee a particular waking experience.