Estimate a bedtime for your chosen wake-up time, or find wake-up times if you go to bed now. Results use approximate 90-minute cycles; actual sleep needs and cycles vary.
I want to wake up at…
:
Ready to go to sleep now?
We'll count 90-minute cycles forward from the current time.
Optimal Times
ℹ️ Includes 15 minutes to fall asleepYour recommended times include an estimated 15 minutes to fall asleep, plus approximately 90 minutes per sleep cycle.
Your Weekly Sleep
See how many hours you slept each day and get personal suggestions.
This Week
Weekly Total—
Daily Average—
Longest Sleep—
Shortest Sleep—
💡 Personalized Suggestions
Add your sleep times to see your weekly suggestions.
Sleep moves through non-REM and REM stages. The NHLBI describes cycles repeating about every 80–100 minutes. Our 90-minute model is a convenient estimate; it cannot measure your sleep stages or guarantee that an alarm will fall between cycles.
1
Light sleep
2
Deep sleep
3
Light sleep
4
REM sleep
~90m
One full cycle
We add a fixed 15-minute allowance to fall asleep, then calculate in 90-minute blocks. Use the suggestions to plan enough time for sleep, and adjust for your own routine.
How much sleep do you actually need?
Sleep needs change across a lifetime. Here's what most sleep researchers recommend as a healthy nightly range by age group.
Age group
Recommended sleep
Teenagers (14–17)
8–10 hours
Young adults (18–25)
7–9 hours
Adults (26–64)
7–9 hours
Older adults (65+)
7–8 hours
Sleep-duration needs vary. See the CDC sleep recommendations by age. Cycle estimates should not be used to reduce the sleep you need.
Simple habits for better sleep
🌙
Keep a consistent schedule
Going to bed and waking up at the same time daily strengthens your body's internal clock.
📵
Dim the screens early
Blue light in the hour before bed can delay melatonin release and push back sleep onset.
☕
Watch late caffeine
Caffeine can stay active in your system for 6+ hours, so an afternoon coffee can still disrupt sleep at night.
🌡️
Cool, dark room
A slightly cool, dark, and quiet bedroom is the environment most linked to deeper sleep.
Frequently asked questions
The calculator estimates bedtimes or wake-up times using 90-minute blocks and a 15-minute allowance to fall asleep. Actual sleep cycles vary, so these are planning estimates, not predictions of your sleep stages.
Prioritize enough sleep rather than an exact cycle count. The CDC recommends at least 7 hours for adults aged 18–60; sleep needs vary by age and person.
This calculator uses a fixed 15-minute allowance for planning. Your own time to fall asleep can be shorter or longer, so adjust your bedtime if needed.
A clock-based calculator cannot tell when your actual sleep cycle ends or guarantee an easier awakening. Allow enough sleep and keep a consistent schedule.
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