Utility
Sleep Cycle Calculator
Best bedtime & wake time by sleep cycles.
Result
11:16 PM
Go to bed for 7.5h sleep (5 cycles)
6 cycles · 9h
09:46 PM
5 cycles · 7.5h
11:16 PM
4 cycles · 6h
12:46 AM
3 cycles · 4.5h
02:16 AM
Find the best bedtime or wake-up time based on 90-minute sleep cycles, so you wake refreshed instead of groggy.
How it works
Each sleep cycle ≈ 90 min, plus ~14 min to fall asleep. Working back (or forward) from your target time gives 4–6 cycle options.
Example
Wake at 7:00 → sleep at 22:16 (5 cycles, 7.5 h) or 20:46 (6 cycles, 9 h).
Popular calculators
The most-used tools on Calcly.