Sleep Calculator

Find the best times to go to bed so you wake up between sleep cycles.

Go to bed at 9:45 PM or 11:15 PM

9hours in bed for 6 cycles

Other options: 12:45 AM (4 cycles, 6 h)

Sleep cycles (recommended): 5
Minutes per cycle: 90

Go to bed at 9:45 PM or 11:15 PM9

This is an educational estimate, not medical advice. Talk to a healthcare professional about your situation.

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How it works

Sleep runs in roughly 90-minute cycles. Waking at the end of a cycle, rather than in deep sleep, tends to feel easier. Most adults need 5–6 cycles (7.5–9 hours).

Formula

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

Example

To wake at 7:00 AM with 15 minutes to fall asleep: bed at 9:45 PM (6 cycles) or 11:15 PM (5 cycles).

Assumptions & limitations

Results are rounded for display.

Frequently asked questions

Are sleep cycles always 90 minutes?

They average about 90 minutes but range from roughly 70 to 120 minutes, so treat these times as a guide.