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Free sleep schedule tool
Find bedtime or wake-up options based on 90-minute sleep cycles and an average 15 minutes to fall asleep.
Sleep result
Five or six sleep cycles are usually the strongest planning targets.
Estimate only. Sleep needs vary by age, health, stress, light exposure, caffeine, and schedule consistency.
The calculator uses common 90-minute sleep cycle planning. For wake-up planning, it subtracts three, four, five, or six cycles from the wake-up time and also subtracts 15 minutes for falling asleep. For sleep-now planning, it starts with the current time, adds 15 minutes to fall asleep, then adds each cycle count.
Sleep moves through lighter sleep, deeper sleep, and REM sleep in repeating patterns. A 90-minute cycle is a simplified average, not a guarantee, but it is useful for planning alarm times that may avoid waking in the middle of deeper sleep.
The calculator does the exact clock math for the time you enter. These examples show how the same 90-minute-cycle idea usually translates into practical bedtime windows.
The highlighted choices are five and six cycles, or about 7.5 to 9 hours of sleep after falling asleep. Four cycles can work for a shorter night, while three cycles is usually a fallback rather than a healthy routine.
Short nights happen, but repeated short sleep can build fatigue. Use the cycle count as a planning signal, then adjust for how you actually feel and what your schedule allows.
Start with the latest bedtime or wake-up time that still gives you five or six cycles, then adjust for your real evening routine. If you know it takes longer than 15 minutes to fall asleep, give yourself more buffer. If you need time for medication, alarms, pets, children, or an early commute, choose the option that protects the morning instead of the one that looks best on paper.
This tool does not diagnose insomnia, sleep apnea, circadian rhythm disorders, shift-work fatigue, jet lag, or medical sleep issues. If sleep problems are persistent or severe, use this calculator only as a planning aid and talk with a qualified health professional.
Do not treat a cycle result as a promise that you will wake refreshed. Caffeine, alcohol, stress, screen use, illness, room temperature, and inconsistent bedtimes can all affect sleep quality. The calculator is best for making a reasonable plan, not for replacing good sleep habits.
Read the sleep cycle calculator guide for a fuller explanation of 90-minute sleep cycles, wake-up planning, sleep-now alarm suggestions, and why the results are estimates rather than medical advice.