Toolstia / sleep calculator
Sleep calculator
Choose a wake-up time to see when to go to bed, or choose a bedtime to see when to wake up, based on 90-minute sleep cycles.
| Go to bed at | Sleep cycles | Sleep |
|---|---|---|
| 9:45 PM | 6 | 9 hours |
| 11:15 PM | 5 | 7.5 hours |
| 12:45 AM | 4 | 6 hours |
| 2:15 AM | 3 | 4.5 hours |
A full sleep cycle lasts about 90 minutes. Waking at the end of a cycle often feels easier than waking in the middle of one. Most adults need 7 to 9 hours of sleep. Cycle length varies from person to person, so treat these times as a guide.
How it works
- Choose wake-up or bedtime mode.
- Set the time and how long you take to fall asleep.
- Pick one of the suggested times.
Sleep cycles
A cycle lasts about 90 minutes. Waking at the end of a cycle often feels easier.
Falling asleep
The calculator adds your time to fall asleep, which is 15 minutes by default.
How much sleep
Most adults need 7 to 9 hours, which is five or six cycles.
A guide only
Cycle length varies between people and through the night.
Questions
How many cycles do I need?
Five or six cycles suits most adults.
Is this medical advice?
No. Talk to a doctor about ongoing sleep problems.
Is my data stored?
Everything is worked out in your browser, and nothing you type is sent anywhere.