Sleep Cycle Calculator

1. 01Choose a modePick "I need to wake up at" to get suggested bed times, or "I am going to bed at" to get suggested wake times.
2. 02Enter the timeYour target wake time or bed time.
3. 03Adjust the fall-asleep buffer (optional)The default is 15 minutes, a commonly cited average. Adjust it if you know you typically take more or less time to fall asleep.

• Planning bed time around a fixed wake-upIf you need to be up at a specific time (an early flight, work, school), see a few bed-time options that align with full sleep cycles.
• Planning a nap or an early nightGoing to bed earlier than usual? See wake times that land at the end of a cycle instead of an arbitrary time.
• Understanding your sleep cycle lengthGet a feel for how many estimated 90-minute cycles fit into a typical night — most adults get roughly 4 to 6 cycles per night.

• Waking at 7:00 AMWith a 15-minute fall-asleep buffer, suggested bed times include 9:15 PM (6 cycles, 9 hours), 10:45 PM (5 cycles, 7.5 hours), and 12:15 AM (4 cycles, 6 hours).
• Going to bed at 10:00 PMWith a 15-minute buffer, suggested wake times include 1:15 AM (3 cycles), 2:45 AM (4 cycles), 4:15 AM (5 cycles), and 5:45 AM (6 cycles).

A sleep cycle moves through several stages (light sleep, deep sleep, and REM sleep). Research describes a typical cycle as lasting approximately 80 to 100 minutes, and cycle length varies by individual and across the course of the night — 90 minutes is a commonly used round-number estimate for planning purposes, not a fixed measurement of any specific cycle. Waking up near the end of an estimated cycle, rather than in the middle of a deep-sleep stage, is commonly reported to feel less groggy — this is the idea behind this calculator's 90-minute planning blocks, though it cannot know exactly where in your cycle you actually are.

The calculator works backward or forward from your target time in steps of 90 minutes (one estimated cycle), for 3, 4, 5, and 6 cycles (4.5, 6, 7.5, and 9 hours of sleep respectively), adding a buffer for the time it typically takes to fall asleep before the first cycle begins.

The 90-minute cycle length is a commonly used planning estimate, not a measurement of your personal sleep — typical sleep cycles are described as roughly 80 to 100 minutes, and actual cycle length and time to fall asleep vary by person, age, and night. This calculator cannot determine your personal sleep stage or know exactly when your cycle ends; it can only suggest approximate times based on a fixed average. This is a scheduling heuristic, not a sleep-tracking device, a diagnosis, or medical advice. If you have ongoing sleep difficulties, consult a healthcare provider.

How long is a sleep cycle?

Typically around 80 to 100 minutes, varying by individual and across the night. This calculator uses 90 minutes — a commonly used round-number estimate — for its planning suggestions, not as a measurement of your actual cycle.

Why does waking up near the end of a cycle matter?

Waking during deep sleep (mid-cycle) is commonly reported to feel groggier than waking near the end of a cycle, when the body is naturally transitioning toward lighter sleep. This calculator times its suggestions in whole 90-minute blocks based on that idea, but it cannot know exactly where in your cycle you actually are without measurement.

How many sleep cycles should I aim for?

Most adults get 4 to 6 cycles (6 to 9 hours) per night. Individual sleep needs vary, so use this as a general guide rather than a strict target.

What is the 15-minute fall-asleep buffer?

It accounts for the time it typically takes to actually fall asleep after getting into bed. You can adjust this if you know you usually take more or less time.

Is this based on my actual sleep data?

No. This calculator uses fixed, commonly cited averages for cycle length and time to fall asleep — it does not track or measure your actual sleep.

Is my data saved?

No. Everything is calculated in your browser; nothing is sent to a server.