Sleep calculator

Estimate bedtime or wake-up times using approximate 90-minute sleep cycles.

21:45 · 6 cycles
23:15 · 5 cycles
00:45 · 4 cycles
02:15 · 3 cycles

Cycle ≈ 90 min + 15 min to fall asleep. An estimate, not medical advice.

Finding a bedtime or wake-up time

Choose whether you know your wake-up time or bedtime, then enter the time in 24-hour format. The tool lists options for three to six approximate 90-minute cycles.

When calculating a bedtime from a wake-up time, it allows an extra 15 minutes for falling asleep. In the opposite mode it adds the cycle durations to the entered bedtime without that extra buffer.

An estimate, not a sleep prescription

Real sleep cycles vary. These suggested times are rough planning aids, not a measurement of your sleep or a guarantee that you will feel rested. The shortest option should not be treated as a recommendation for sufficient sleep.

This tool does not diagnose or treat sleep problems. Its Ukrainian and English versions use the same calculation.