Health
Sleep Cycle Calculator
Find the best time to go to bed or wake up based on 90-minute sleep cycles, so you wake up feeling refreshed.
Go to sleep at one of these times:
9:45 PM
6 cycles · 9 h
11:15 PM
5 cycles · 7.5 h
12:45 AM
4 cycles · 6 h
2:15 AM
3 cycles · 4.5 h
Includes about 15 minutes to fall asleep. 5–6 cycles is ideal for most adults.
Sleep Cycle Calculator
Find the best time to go to bed or wake up based on 90-minute sleep cycles, so you wake up feeling refreshed.
The Sleep Calculator helps you determine the best times to go to bed or wake up based on natural 90-minute human sleep cycles. By timing your sleep in these intervals, you can feel more rested and alert when you wake up.
To use the calculator, choose between 'I want to wake up at' or 'I'm going to bed at'. Enter your target time. The tool will then provide a list of recommended times calculated to fit within 5–6 sleep cycles.
For example, if you want to wake up at 7:00 AM, the tool might suggest going to bed at 10:00 PM or 11:30 PM, as these times ensure you complete full sleep cycles. This method accounts for the roughly 15 minutes it takes to fall asleep.
Remember that these are estimates. Factors like stress or environment can change how long it takes you to fall asleep. This tool runs in your browser to help you plan your sleep without storing any personal information.
Key Features
- Sleep Cycle Calculator: 100% free, no sign-up
- Instant results as you type
- Private: runs in your browser
- Works on phone, tablet and desktop
- Available in English, Spanish, French and Arabic
How it works
The calculator calculates wake/sleep times by using multiples of 90-minute sleep cycles plus a 15-minute average period for falling asleep.
Worked example
Frequently asked questions
Is a 90-minute cycle fixed?
It is an average. Individual sleep cycles can vary slightly from person to person.
Why the 15-minute buffer?
It is the average time a healthy sleeper takes to drift off into stage 1 sleep.
How many cycles do I need?
Most adults require 5–6 full sleep cycles to feel fully rested each night.
Does this account for naps?
The tool is designed for primary overnight sleep planning.
Is my sleep data tracked?
No, all inputs are processed purely within your browser; nothing is tracked or stored.