Sleep Cycle Calculator

Calculate optimal bedtime and wake time based on 90-minute sleep cycles to wake between cycles.

Wake-Up Hour (24h)

Wake-Up Minute

Time to Fall Asleep

min

Target Sleep Cycles

Tab to move between fields

Ideal Bedtime

23:15

Total Sleep7.5 hrs

4 Cycles (6 hrs)00:45

5 Cycles (7.5 hrs)23:15

6 Cycles (9 hrs)21:45

Fall Asleep Buffer15 min

How to Use This Calculator

Enter your required wake-up time using the 24-hour hour and minute fields.
Set how long it typically takes you to fall asleep in minutes.
Select your target number of sleep cycles (4 cycles = 6 hrs, 5 = 7.5 hrs, 6 = 9 hrs).
Review the Ideal Bedtime output and set an alarm accordingly.
Compare the 4-, 5-, and 6-cycle bedtime options to find the most practical fit for your schedule.

What each input means

Identify Input Parameters
4 parameters
Wake-Up Hour (24h) = 7, Wake-Up Minute = 0, Time to Fall Asleep = 15, Target Sleep Cycles = 5 = 4 input(s) provided
Calculate Ideal Bedtime
Ideal Bedtime = formatTime(bedtimeHour
23:15 = 23:15
Calculate Total Sleep
Total Sleep
7.5 = 7.5
Calculate 4 Cycles
00:45 = 00:45

Engine last updated August 5, 2026. Checked against 3 independently-derived tests — how we verify calculators.

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