Sleep Cycle Calculator

Plan your night around 90-minute sleep cycles. Pick a wake-up time and see when to head to bed, or set a bedtime and see when to wake up.

Plan your night around 90-minute sleep cycles so you wake up at the end of a cycle rather than in the middle of deep sleep. Enter the time you want to wake up and this sleep calculator shows the best bedtimes, or set a bedtime and see the best times to wake up.

Plan your sleep

I want to plan by

Head to bed at one of these times

9:45 pm

6 cycles · 9h of sleep

Ideal

11:15 pm

5 cycles · 7h 30m of sleep

Ideal

12:45 am

4 cycles · 6h of sleep

A general sleep-planning helper, not medical advice. The 90-minute cycle and 15 minutes to fall asleep are averages. People differ night to night, so treat these as a guide.

How it works

  1. 1

    Pick a mode

    Choose whether you know your wake-up time or your bedtime.

  2. 2

    Enter the time

    Type in the time you want to wake up, or the time you plan to go to bed.

  3. 3

    Read the options

    Each suggested time lands at the end of a full cycle. The best picks, 5 or 6 cycles, are highlighted.

Instant & 100% private — nothing is uploaded

Every calculation runs locally in your browser. The measurements, dates and details you enter stay on your own device and are never sent to a server — nothing is stored, logged or shared.

Frequently asked questions

Why 90-minute cycles?
Your sleep runs in cycles of about 90 minutes, moving from light to deep to REM sleep. Waking at the end of a cycle, instead of partway through deep sleep, usually feels less groggy.
Why add 15 minutes?
Most people take about 15 minutes to fall asleep after getting into bed, so every time here builds in that gap. If you drop off faster or slower, shift the times to match.
How many cycles should I aim for?
Five or six cycles, about 7.5 to 9 hours, suit most adults. That's why those two options are highlighted. Four cycles (6 hours) gets you through in a pinch, but you'll feel it.
Are these times exact?
No. Cycle length and how long you take to fall asleep vary from person to person and night to night, so treat these as a guide rather than a precise schedule.

Important

These calculators give general, informational estimates and are not medical advice, diagnosis or treatment. Everyone is different — for decisions about your health, talk to a qualified clinician.

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