Time & Date
Sleep Time Calculator
Find what time to go to bed, given a wake-up time and desired hours of sleep.
—
Formula
Bedtime = wake-up time minus desired sleep duration, wrapped around the 24-hour clock.
How it works
Enter the time you must wake up and how many hours of sleep you want. The calculator subtracts the sleep duration and gives the bedtime, wrapping past midnight where needed.
FAQs
Does it include time to fall asleep?
No. It counts sleep itself only; if you usually take time to fall asleep, go to bed that much earlier.
What if I want 7.5 hours?
Fractional hours work: 7.5 hours is 7 hours 30 minutes.
Is this medical advice?
No. It is a simple time calculation; sleep needs vary by person.