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Sleep Cycle Calculator

Use this free sleep cycle calculator to work out good bedtimes for the time you want to wake up. Enter your numbers and the results update as you type. It runs in your browser, so nothing you enter is uploaded, and there is nothing to sign up for.

Runs in your browser. Your files never leave your device.

Go to bed at (6 cycles, 9 h)
21:15
5 cycles (7.5 h)
22:45
4 cycles (6 h)
00:15
Sleep cycles last about 90 minutes and most people need around 15 minutes to fall asleep. This is a rough guide, not medical advice.

How it works

  1. 01Enter your numbers in the fields.
  2. 02The results update as you type.
  3. 03Change a value to compare what-if cases.

Questions

How do sleep cycles work?

Sleep moves through stages in cycles of about 90 minutes. Waking at the end of a cycle often feels easier. This is a rough guide, not medical advice.

Is my data saved or sent anywhere?

No. The calculation runs in your browser and nothing is uploaded.

Are the results exact?

The maths is exact for the values you enter, but real life can differ because of fees, taxes and changing rates. Use the result as a guide.

Is my file uploaded to a server?

No. Everything happens inside your browser on your own device. Your files are never sent to us or anyone else.

Is it free?

Yes. It is free to use, with no signup, no watermark and no daily limit.

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