Sleep Schedule Calculator
Find bedtimes aligned to 90-min sleep cycles.
Calculate ideal sleep and wake times by sleep cycles instantly. Free 90-minute cycle sleep calculator.
Calculator Inputs
About Sleep Cycles
Find bedtimes aligned to 90-min sleep cycles.
Counts back in complete 90-minute cycles to avoid waking mid-cycle.
Where it is used
Better sleep hygiene, jetlag management.
How to use the Sleep Cycles
- Wake Time (HH:MM) — enter the value (e.g. 06:30).
- Calculate — press the Calculate button to see the result instantly above.
Formula
wake - N×90min - 15min fall-asleep buffer.
Examples
Example
wake:06:30
Result: Sleep by 22:15 → wake refreshed (6 cycles)
Frequently Asked Questions
- Why 90 minutes?
- Average human sleep cycle duration is ~90 minutes.