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Free Sleep Cycle Calculator — Best Bedtime & Wake Time
Free Sleep Cycle Calculator is a free online tool by US AI. It counts backwards (or forwards) in 90-minute sleep cycles so you wake up between cycles — feeling fresher.
Based on average 90-minute sleep cycles + ~15 min to fall asleep. Averages only — not medical advice.
📖 How to use
- Choose a mode: 'I wake up at…' or 'I sleep now'.
- Enter your wake-up time (or just tap Calculate for right-now).
- Pick one of the suggested times — 5 cycles is the sweet spot for most adults.
✨ Why use this tool?
US AI's sleep calculator uses simple, honest cycle math — no account, no tracking. Remember: cycles are averages; this is not medical advice.