Sleep Cycle Calculator
Free sleep cycle calculator: find the best time to wake up or go to bed using 90-minute cycles. Wake feeling refreshed. No sign-up.
Settings
Go to bed by
- 4 cycles (~6 hours): go to bed by 12:45 AM
Wake at 7:00 AM
- 5 cycles (~7.5 hours): go to bed by 11:15 PM
Wake at 7:00 AM
- 6 cycles (~9 hours): go to bed by 9:45 PM
Wake at 7:00 AM
Find the best time to wake up or go to bed with our free sleep cycle calculator. Sleep runs in roughly 90-minute cycles through light sleep, deep sleep, and REM; waking between cycles can help you feel more refreshed and less groggy than waking in the middle of deep sleep. Whether you need to be up at 7 AM and want a suggested bedtime, or you're heading to bed now and need an alarm time, this wake-up calculator gives you options for 4, 5, and 6 full cycles so you can plan restful sleep. Adjust how long it takes you to fall asleep and your cycle length if needed. No sign-up — everything runs in your browser.
How to Use Sleep Cycle Calculator
Choose Wake-At or Bed-At Mode
Select "Wake at" when you have a fixed wake time (e.g. for work or school) and want to know when to go to bed so you wake at the end of a cycle. Select "Bed at" when you're going to bed now or at a set time and want to know the best time to set your alarm for a refreshed wake-up.
Enter Your Time
In "Wake at" mode, enter the time you need to wake up (e.g. 7:00 AM). In "Bed at" mode, enter when you plan to go to sleep (e.g. 11:00 PM). Use the time picker; the tool works in 24-hour time and displays results in an easy-to-read format.
Adjust Fall-Asleep and Cycle Length (Optional)
Most people take around 15 minutes to fall asleep; the default is 15. A full sleep cycle is typically 90 minutes (light sleep, deep sleep, REM). You can change the cycle length to 95 minutes if that fits you better. The calculator uses these values to compute your ideal bed or alarm times.
Pick Your Preferred Cycle Option
You'll see three options: 4, 5, and 6 cycles — about 6, 7.5, and 9 hours of sleep. Choose the one that fits your schedule and sleep needs. Set your alarm for the suggested wake time, or aim to be in bed by the suggested bedtime to wake feeling more rested.
Calculator Features
Two Modes: Wake At or Bed At
Enter your target wake time to get recommended bed times, or your bedtime to get recommended alarm times. One tool for both "when should I wake up?" and "when should I go to bed?" planning.
4, 5, and 6 Cycle Options
See options for 4, 5, and 6 full sleep cycles (about 6, 7.5, and 9 hours). Choose how much sleep you want and get a clear bed or wake time for each.
90-Minute Sleep Cycles
Based on the typical 90-minute sleep cycle (light, deep, REM). Waking between cycles can reduce morning grogginess compared to waking in deep sleep.
Adjustable Fall-Asleep Time
Set how long it usually takes you to fall asleep (default 15 min). The calculator adds this before the first full cycle for more accurate timing.
Instant Results
Results update as you change the time, mode, or settings. No submit button — ideal for trying different wake or bed times quickly.
Free and Private
All calculations run in your browser. No sign-up, no data stored or sent to servers.
Complete Function List
- Wake-at mode: enter wake time, get bed times for 4, 5, 6 cycles
- Bed-at mode: enter bed time, get wake times for 4, 5, 6 cycles
- 90-minute sleep cycle (configurable 60–120 min):
- Adjustable fall-asleep time (default 15 min):
- Clear labels: e.g. "6 cycles (~9 hours)" with 12-hour display
- Instant update on any change:
- No account, no data stored:
- Works on desktop and mobile:
Common Calculations & Examples
Example 1: I need to wake at 7:00 AM — when should I go to bed?
Problem: You have to get up at 7:00 AM for work or school and want to wake at the end of a sleep cycle so you feel less groggy and more refreshed.
Steps:
- Select "Wake at" and enter 7:00 AM.
- Leave fall-asleep at 15 min and cycle length at 90 min (or adjust if you prefer).
- Read the three options: e.g. "6 cycles (~9 hours): go to bed by 9:45 PM."
Explanation: Waking at the end of a cycle (in lighter sleep) often feels better than waking in the middle of deep sleep. The calculator adds your fall-asleep time and then full 90-minute cycles to give you precise bed or alarm times.
Example 2: I’m going to bed at 11:00 PM — when should I set my alarm?
Problem: You plan to go to bed at 11:00 PM and want to know the best time to set your alarm so you wake between cycles.
Steps:
- Select "Bed at" and enter 11:00 PM (23:00).
- Use default 15 min fall-asleep and 90 min cycles.
- Check the suggested wake times for 4, 5, and 6 cycles.
Explanation: The tool adds 15 minutes to fall asleep, then 4, 5, or 6 full cycles, so you wake between cycles instead of in the middle of one — helping you feel more rested when you get up.