Wake Up Time Calculator
Best bedtimes based on 90-minute sleep cycles.
Enter your values
ⓘ Live results
Results
- Best bedtime (6 cycles)
- 21:45
- 5 cycles (7.5 h)
- 23:15
- 4 cycles (6 h)
- 00:45
- Fall-asleep allowance
- 15 min
Quick answer
Waking at the end of a 90-minute cycle feels easier than waking mid-cycle, so bedtimes should be set in 90-minute steps.
bedtime = wake time - (cycles x 90 min) - fall-asleep time
How to use the Wake Up Time Calculator
- 1Enter the time your alarm goes off.
- 2Allow 10-20 minutes to actually fall asleep.
- 3Pick the bedtime that gives you five or six full cycles.
Worked example
Using the values the calculator loads with:
Inputs
- Wake hour (24h)7
- Wake minute0
- Time to fall asleep15 min
Results
- Best bedtime (6 cycles)21:45
- 5 cycles (7.5 h)23:15
- 4 cycles (6 h)00:45
- Fall-asleep allowance15 min
Frequently asked questions
Are cycles always 90 minutes?
They range from 80 to 110 minutes and change through the night; treat this as a guide.
Is six cycles always best?
Nine hours suits some people; most adults do well on five or six cycles.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.