Free sleep calculator
Sleep calculator
This free sleep calculator works out bedtimes and wake-up times in 90-minute sleep cycles. To wake up at 7:00 am, go to bed at 9:45 pm (9 hours of sleep), 11:15 pm (7.5 hours), or 12:45 am (6 hours). Each bedtime allows 15 minutes to fall asleep and ends on a full 90-minute sleep cycle.
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Bedtimes for a 7:00 am wake-up
9:45 pm
9 hours · 6 cycles
Recommended
11:15 pm
7.5 hours · 5 cycles
Recommended
12:45 am
6 hours · 4 cycles
Short night
Adults aged 18 to 60 years need 7 or more hours of sleep, according to the CDC. Times include 15 minutes to fall asleep.
Bedtimes for common wake-up times
Find your wake-up time, then pick a bedtime from the same row. Each one allows 15 minutes to fall asleep. Adults should aim for 7.5 or 9 hours; teens should aim for 9.
| Wake up at | 9 hours (6 cycles) | 7.5 hours (5 cycles) | 6 hours (4 cycles) |
|---|---|---|---|
| 4:00 am | 6:45 pm | 8:15 pm | 9:45 pm |
| 4:30 am | 7:15 pm | 8:45 pm | 10:15 pm |
| 5:00 am | 7:45 pm | 9:15 pm | 10:45 pm |
| 5:30 am | 8:15 pm | 9:45 pm | 11:15 pm |
| 6:00 am | 8:45 pm | 10:15 pm | 11:45 pm |
| 6:30 am | 9:15 pm | 10:45 pm | 12:15 am |
| 7:00 am | 9:45 pm | 11:15 pm | 12:45 am |
| 7:30 am | 10:15 pm | 11:45 pm | 1:15 am |
| 8:00 am | 10:45 pm | 12:15 am | 1:45 am |
| 8:30 am | 11:15 pm | 12:45 am | 2:15 am |
| 9:00 am | 11:45 pm | 1:15 am | 2:45 am |
| 9:30 am | 12:15 am | 1:45 am | 3:15 am |
| 10:00 am | 12:45 am | 2:15 am | 3:45 am |
Wake-up times for common bedtimes
Going to bed at a set time? These wake-up times finish a full sleep cycle, again with 15 minutes to fall asleep.
| Go to bed at | 6 hours (4 cycles) | 7.5 hours (5 cycles) | 9 hours (6 cycles) |
|---|---|---|---|
| 8:00 pm | 2:15 am | 3:45 am | 5:15 am |
| 8:30 pm | 2:45 am | 4:15 am | 5:45 am |
| 9:00 pm | 3:15 am | 4:45 am | 6:15 am |
| 9:30 pm | 3:45 am | 5:15 am | 6:45 am |
| 10:00 pm | 4:15 am | 5:45 am | 7:15 am |
| 10:30 pm | 4:45 am | 6:15 am | 7:45 am |
| 11:00 pm | 5:15 am | 6:45 am | 8:15 am |
| 11:30 pm | 5:45 am | 7:15 am | 8:45 am |
| 12:00 am | 6:15 am | 7:45 am | 9:15 am |
| 12:30 am | 6:45 am | 8:15 am | 9:45 am |
| 1:00 am | 7:15 am | 8:45 am | 10:15 am |
How much sleep do you need?
Most adults need 7 or more hours of sleep a night, teens need 8 to 10 hours, and children aged 6 to 12 need 9 to 12 hours, according to the CDC. Babies and toddlers have shorter sleep cycles and nap during the day, so this calculator is for ages 6 and up.
| Age group | Ages | Recommended sleep |
|---|---|---|
| Children | 6 to 12 years | 9 to 12 hours |
| Teens | 13 to 17 years | 8 to 10 hours |
| Adults | 18 to 60 years | 7 or more hours |
| Adults | 61 to 64 years | 7 to 9 hours |
| Older adults | 65 and older | 7 to 8 hours |
How the sleep calculator works
Sleep runs in cycles of light sleep, deep sleep, and REM sleep. Each cycle lasts about 90 minutes on average, though cycles vary from person to person and through the night. Waking at the end of a cycle, when sleep is lighter, tends to feel easier than waking from deep sleep.
The calculator counts whole 90-minute cycles back from your wake-up time, or forward from your bedtime, and adds the time it usually takes you to fall asleep. Pick your age to see which options give you enough total sleep.
Treat the results as a starting point. If you still wake up groggy, move your bedtime 15 minutes earlier or later for a week and see how you feel. Getting enough total sleep matters more than hitting an exact cycle, and keeping the same schedule every day, including weekends, helps too.
For wind-down routines, breathing exercises, and Yoga Nidra, see our sleep resources.
Frequently asked questions
What time should I go to bed to wake up at 6 am?
To wake up at 6:00 am, go to bed at 8:45 pm (9 hours of sleep), 10:15 pm (7.5 hours), or 11:45 pm (6 hours). Each bedtime allows 15 minutes to fall asleep and ends on a full 90-minute sleep cycle. Most adults need at least 7 hours, so 8:45 pm or 10:15 pm is the better target.
If I go to bed at 11 pm, when should I wake up?
If you go to bed at 11:00 pm, wake up at 5:15 am (6 hours of sleep), 6:45 am (7.5 hours), or 8:15 am (9 hours). Each time allows 15 minutes to fall asleep and ends on a full 90-minute sleep cycle. Most adults need at least 7 hours, so 6:45 am or 8:15 am is the better target.
Why does a sleep calculator use 90-minute cycles?
Sleep moves through light, deep, and REM stages in cycles that last about 90 minutes on average. Waking at the end of a cycle, when sleep is lighter, usually feels easier than waking from deep sleep. Cycle length varies from person to person, so treat the times as estimates.
How much sleep do I need?
Adults aged 18 to 60 need 7 or more hours a night, teens need 8 to 10 hours, and children aged 6 to 12 need 9 to 12 hours, according to the CDC.
Why does the calculator add 15 minutes to fall asleep?
Most people take a little while to drift off. Falling asleep within 30 minutes is one sign of good sleep quality, according to the National Sleep Foundation. Change the setting to match how long it usually takes you.
Is 6 hours of sleep enough?
For most people, no. Six hours is four sleep cycles, which is less than the 7 or more hours adults need and well short of the 8 to 10 hours teens need. Save 6-hour bedtimes for an occasional short night.
Sources
- Centers for Disease Control and Prevention. About Sleep: recommended hours of sleep by age.
- Watson NF, et al. Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep, 2015.
- Paruthi S, et al. Recommended amount of sleep for pediatric populations: a consensus statement of the American Academy of Sleep Medicine. Journal of Clinical Sleep Medicine, 2016.
- Ohayon M, et al. National Sleep Foundation's sleep quality recommendations: first report. Sleep Health, 2017.
- Patel AK, et al. Physiology, Sleep Stages. StatPearls, NCBI Bookshelf.