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Sleep Calculators

Sleep Cycle Calculator

How many 90-minute sleep cycles fit into your sleep window, and the ideal duration for whole cycles.

Also known as 90 minute sleep cycles, rem cycles, sleep cycle length.

Enter values

Results update as you type.

Result

Sleep cycles

5

Ideal sleep (whole cycles)
7.5 hours
Minutes into current cycle
0 min

About the Sleep Cycle Calculator

How many 90-minute sleep cycles fit into your sleep window, and the ideal duration for whole cycles.

Also known as: 90 minute sleep cycles, rem cycles, sleep cycle length.

How to use this calculator

  1. Enter hours of sleep, cycle length.
  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.

Sleep Cycle formula

Cycles = sleep minutes ÷ cycle length

Worked example

Using the values pre-filled in the calculator above:

  • Hours of sleep = 7.5
  • Cycle length = 90 min

the calculator returns:

  • Sleep cycles: 5
  • Ideal sleep (whole cycles): 7.5 hours
  • Minutes into current cycle: 0 min