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Health & Fitness · Free tool

Sleep Cycle Calculator

Pick a wake-up time and see the best bedtimes aligned with 90-minute sleep cycles. Or enter bedtime, get wake times.

Updated April 2026

Try going to bed at

  • 21:466 cycles · 9h sleep
  • 23:165 cycles · 7h 30m sleep
  • 00:464 cycles · 6h sleep
  • 02:163 cycles · 4h 30m sleep

Assumes ~14 min to fall asleep and 90-min sleep cycles. Waking at the end of a cycle feels more refreshing than waking mid-cycle.

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What it does

Pick a wake-up time and see the best bedtimes aligned with the 90-minute sleep cycle — waking at the end of a cycle feels less groggy than waking in the middle. Or enter bedtime and get wake times. Accounts for typical sleep-onset latency.

Pair with heart rate zone calculator, caffeine intake calculator, water intake calculator, and BMR calculator.

How to use it

  1. Pick wake-up time or bedtime.
  2. Adjust the typical time to fall asleep (default 15 min).
  3. Read the recommended bedtimes or wake times.
  4. Pick the one that gets you 5 or 6 full cycles.