Sleep Calculator
Sleep Calculator — free online tool. Quick and easy to use.
Sleep Cycle Calculator
Wake up feeling refreshed by timing your sleep to complete 90-minute sleep cycles. Our calculator suggests optimal bedtimes and wake-up times based on sleep science.
How Sleep Cycles Work
Sleep occurs in cycles of approximately 90 minutes. Each cycle includes light sleep, deep sleep, and REM (dreaming) sleep. Waking up at the end of a cycle — rather than in the middle — leaves you feeling more alert and refreshed.
How Many Cycles Do You Need?
- Adults (18-64): 5-6 cycles (7.5-9 hours)
- Teenagers (14-17): 5-6 cycles (8-10 hours)
- Older adults (65+): 4-5 cycles (7-8 hours)
How to Use
- Enter your desired wake-up time OR bedtime
- Click Calculate to see optimal times
- Each suggested time aligns with complete sleep cycles
- Allow 15-20 minutes to fall asleep when planning
Tips for Better Sleep
- Go to bed and wake up at consistent times, even on weekends
- Keep your bedroom cool, dark, and quiet
- Avoid screens for 30-60 minutes before bedtime
- Limit caffeine after 2 PM