Sleep Hours Calculator
Enter your bedtime and wake up time to see how many hours you sleep and how that compares with what you need.
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Free sleep hours calculator. Enter bedtime and wake up time to see hours slept across midnight, sleep cycles and whether you meet your target.
Sleep hours calculator
Enter the time you go to bed and the time you wake up. The calculator handles nights that cross midnight, subtracts the time you take to fall asleep and compares the result with your target.
How to calculate hours of sleep between two times
Take the wake time, subtract the bedtime and, if the answer is negative, add 24 hours because you slept across midnight. Then subtract the minutes it took you to fall asleep. From 10:00 PM to 6:00 AM is 8 hours in bed. With 15 minutes to fall asleep, the estimated sleep is 7 hours 45 minutes.
The same method answers common searches such as how many hours is 10 PM to 6 AM, how many hours is 11 PM to 7 AM, or how long is 9 PM to 5 AM. Time in bed is not the same as time asleep, so a night of 8 hours in bed usually delivers a little less actual sleep.
Quick reference: common bedtime and wake time pairs
| Bedtime | Wake up | Time in bed | Sleep with 15 minutes to fall asleep |
|---|---|---|---|
| 9:00 PM | 5:00 AM | 8 hours | 7 hours 45 minutes |
| 10:00 PM | 6:00 AM | 8 hours | 7 hours 45 minutes |
| 10:30 PM | 6:30 AM | 8 hours | 7 hours 45 minutes |
| 11:00 PM | 6:00 AM | 7 hours | 6 hours 45 minutes |
| 11:00 PM | 7:00 AM | 8 hours | 7 hours 45 minutes |
| 12:00 AM | 7:00 AM | 7 hours | 6 hours 45 minutes |
| 1:00 AM | 7:00 AM | 6 hours | 5 hours 45 minutes |
| 2:00 AM | 8:00 AM | 6 hours | 5 hours 45 minutes |
Adults need 7 or more hours according to the CDC and the American Academy of Sleep Medicine. See how many hours of sleep you need and whether 6 hours is enough.
What to do with the result
If you are short, use the bedtime calculator to set an earlier lights out, then track the total with the sleep debt calculator. To see how the number splits into cycles, open the sleep cycles per night calculator.
Frequently asked questions
How many hours of sleep is 10 PM to 6 AM?
It is 8 hours in bed. With 15 minutes to fall asleep, the estimated sleep is about 7 hours 45 minutes.
How do I calculate sleep time across midnight?
Subtract the bedtime from the wake time and add 24 hours if the result is negative. Then subtract the time it takes you to fall asleep.
Is time in bed the same as sleep?
No. Time in bed includes the time you take to fall asleep and any awake time in the night, so actual sleep is usually a little lower.
How many hours of sleep do adults need?
Adults aged 18 to 60 need 7 or more hours, and the National Sleep Foundation range is 7 to 9 hours.
Is 6 hours of sleep enough?
For most adults it is below the recommended 7 hours. Some people feel fine for a while, but research on chronic sleep restriction found that performance slips even when people do not feel very sleepy. Treat 6 hours as a short night and plan recovery sleep.
How do I move my bedtime earlier?
Shift it by 15 to 30 minutes every two or three days while keeping the wake time fixed, get bright light after waking and dim lights for an hour before bed.
Will waking at the end of a cycle remove morning grogginess?
It can help some people, because waking from light sleep is usually easier than waking from deep sleep. The effect is not guaranteed. Grogginess, known as sleep inertia, usually fades within 15 to 30 minutes and also depends on how much sleep you had and when you wake in your body clock.
Why am I still tired after 8 or 9 hours of sleep?
Common reasons include irregular sleep times, alcohol or late caffeine, a warm or noisy room, waking at the wrong point in a cycle, or sleep that is fragmented. Loud snoring with breathing pauses, or sleepiness that affects driving or work, should be checked by a doctor.