Sleep Calculator - Best Time to Sleep & Wake Up

This sleep calculator helps you find the best time to go to sleep based on your desired wake-up time. It uses 90-minute sleep cycles plus average time to fall asleep so you can wake up between cycles and feel less groggy.

Suggested times to fall asleep:

These times are based on 90-minute sleep cycles plus the time it takes you to fall asleep. Waking up at the end of a cycle usually feels better than waking up in the middle of deep sleep.

How this sleep calculator works

Sleep is organized in cycles of about 90 minutes. Waking up at the end of a cycle usually feels easier than waking up in the middle of deep sleep. This calculator counts backwards from your desired wake time using:

90-minute sleep cycles
4–6 cycles (about 6–9 hours of sleep)
extra time for you to fall asleep (10–30 minutes)

The output shows several suggested times to fall asleep, not just go to bed. If you need to wake up at 07:00 and usually fall asleep in 15 minutes, the calculator will show times that should line up with the end of 4, 5 or 6 sleep cycles.

This tool is for general information only and does not replace medical advice. Sleep quality depends on stress, light, caffeine, alcohol, health and many other factors.