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Sleep Calculator
sleep calculator · sleep cycle · bedtime calculator · 수면 시간
Sleep Calculator
Find the ideal sleep or wake-up times based on 90-minute sleep cycles
Assumes ~14 minutes to fall asleep. Each sleep cycle is 90 minutes.
How to use
- 1
Choose wake-up or bedtime.
- 2
Enter your time.
- 3
Pick a cycle-aligned time.
FAQ
Is this tool free?
Yes — no sign-up, no installation, completely free to use right away.
What is this tool?
This tool suggests the best times to go to bed or wake up based on sleep cycles. Tell it when you need to wake up, and it works back through full cycles so you rise feeling refreshed. It's a small change that can make mornings noticeably easier. Everything is calculated in your browser, with nothing stored.