Calculate the best bedtime or wake-up time based on 90-minute sleep cycles. Free online Sleep Calculator that works directly in your browser.
A sleep cycle lasts about 90 minutes and includes Light Sleep, Deep Sleep, and REM Sleep.
Waking up near the end of a sleep cycle usually helps you feel more refreshed than waking up during deep sleep.
Most healthy adults sleep best with 5 complete sleep cycles (about 7½ hours).
Yes. It's completely free and works directly in your browser.
A sleep cycle lasts about 90 minutes and includes light, deep, and REM sleep.
| Cycles | Sleep | Recommendation |
|---|---|---|
| 3 | 4h 30m | Too Little |
| 4 | 6h | Minimum |
| 5 | 7h 30m | ⭐⭐⭐⭐⭐ Recommended |
| 6 | 9h | Great for Recovery |
Most people complete one sleep cycle in about 90 minutes, making wake-up times more natural.
Most adults benefit from 5–6 sleep cycles, or about 7.5–9 hours.
Yes. The calculator adds about 15 minutes for falling asleep.
No. Everything is calculated locally in your browser.
Yes. It works on phones, tablets, and desktop browsers.