Calculate your ideal bedtime & wake-up time based on natural human sleep cycles
This free sleep calculator helps you work out the best bedtime to wake up feeling refreshed, not groggy. Human sleep runs in cycles of roughly 90 minutes, mixing light sleep, deep sleep and REM dream sleep. Waking mid-cycle causes sleep inertia and tiredness; waking at the end of a full cycle leaves you energized.
Our bedtime calculator accounts for the average time people take to fall asleep. Simply pick your target wake-up hour, adjust your sleep onset delay, and the tool instantly shows all ideal bedtimes matching complete sleep cycles. This sleep time calculator is widely used by students, shift workers, parents and fitness fans searching for optimal sleep schedules.
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No sign-up, no pop-up login walls, no download required. All calculations run inside your browser instantly, no data sent to external servers. Unlike paid sleep trackers, our sleep cycle calculator is 100% free for unlimited daily use. If you search for a simple, fast sleep calculator to plan your night rest, this page is built to rank top on Google against sleepcalculator.com.
Whether you need a quick bedtime check before work, a nap cycle planner for daytime rest, or a long-term sleep schedule tracker, our all-in-one sleep calculator covers every common sleep planning need without complicated settings.