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Bedtime Calculator

Best times to go to bed to wake up refreshed at the end of a 90-minute sleep cycle.

Enter values

Results update as you type.

Result

Best bedtimes

21:15 or 22:45

Waking at the end of a cycle usually feels better than waking mid-cycle.

6 cycles (9.0 h sleep)
21:15
5 cycles (7.5 h sleep)
22:45
4 cycles (6.0 h sleep)
00:15
3 cycles (4.5 h sleep)
01:45

About the Bedtime Calculator

Best times to go to bed to wake up refreshed at the end of a 90-minute sleep cycle.

Also known as: when should i go to sleep, sleep calculator, bed time calculator.

How to use this calculator

  1. Enter i need to wake up at, time to fall asleep.
  2. The result updates instantly as you type — press Calculate (or Enter) at any time.
  3. Review the breakdown shown under the main result.
  4. Use Copy result or Share to save the answer or send a link with your inputs.

Formula

Bedtime = wake time − (cycles × 90 min) − time to fall asleep

Worked example

Using the values pre-filled in the calculator above:

  • I need to wake up at: 06:30
  • Time to fall asleep = 15 min

the calculator returns:

  • Best bedtimes: 21:15 or 22:45
  • 6 cycles (9.0 h sleep): 21:15
  • 5 cycles (7.5 h sleep): 22:45
  • 4 cycles (6.0 h sleep): 00:15