Sleep Cycle Calculator
Bedtimes or wake-up times that line up with 90-minute sleep cycles. Results update as you type.
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Results
Fill in the details above and the results appear here.
About the Sleep Cycle Calculator
Pick a wake-up time and see which bedtimes line up with complete sleep cycles, or pick a bedtime and see when to wake. Waking at the end of a cycle, rather than in the middle, is often described as feeling easier.
It also lets you set how long you usually take to fall asleep and your own cycle length.
The calculation runs in your browser, so the numbers you enter are not uploaded or stored.
Sleep Cycle Calculator example
Wake-up time: 06:30
Minutes to fall asleep: 15 min
Cycle length: 90 min6 cycles · 9 h of sleep: 9:15 PM
5 cycles · 7 h 30 min of sleep: 10:45 PM
4 cycles · 6 h of sleep: 12:15 AM
3 cycles · 4 h 30 min of sleep: 1:45 AMHow it is calculated
One sleep cycle is commonly quoted as about 90 minutes. The calculator multiplies the number of cycles by the cycle length, then adds or subtracts the time you take to fall asleep.
Sleep time = cycles × cycle length (90 min by default)Bedtime = wake-up time − sleep time − time to fall asleepWake-up time = bedtime + time to fall asleep + sleep time
What to enter
- Minutes to fall asleep. Blank = 15 minutes.
- Cycle length. Blank = 90 minutes, the commonly quoted average.
How to use the Sleep Cycle Calculator
- Fill in the fields above. Required fields are marked, optional ones can be left blank and fall back to the defaults described on this page.
- Use “Try an example” to see a worked case, then replace the numbers with your own.
- Read the results as you type. The large card is the main answer and the smaller cards are the related figures.
- Copy a single value or everything, or share a link that keeps your inputs.
Sleep Cycle Calculator FAQ
How does the sleep cycle calculator work?
One sleep cycle is commonly quoted as about 90 minutes. The calculator multiplies the number of cycles by the cycle length, then adds or subtracts the time you take to fall asleep.
How many cycles should I aim for?
Five cycles (7.5 hours) is the option most often suggested for adults, with four to six as a typical range. How much sleep you need varies by person, age and health.
Is 90 minutes exact?
No. Cycle length varies between people and through the night. Treat the times as a starting point and adjust if you still feel tired. This is not medical advice.
Is this sleep cycle calculator free and private?
Yes. It is free with no sign-up, and the calculation happens on your device, so your numbers are never sent to a server.
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