How many hours of sleep am I actually getting?

Less than your time in bed. Subtract the time it takes to fall asleep (10 to 20 minutes for most people) and any time awake during the night. Eight hours in bed is typically closer to seven hours of sleep.

How many hours is 11 PM to 6 AM?

Seven hours in bed, which is about 6 hours 45 minutes of sleep once you subtract the time it takes to fall asleep. That is 4 complete 90-minute cycles plus 45 minutes into a fifth.

Is 6 hours of sleep enough?

For almost everyone, no. Six hours is 4 cycles, below the 7 to 9 hour adult recommendation. A small minority carry a genetic short-sleep variant, but people who feel fine on six hours are usually adapted to impairment rather than free of it.

Does time in bed count as sleep?

Not for any purpose that matters. The ratio of sleep to time in bed is called sleep efficiency, and below 85% is the point where lying awake in bed starts to become a habit in itself.

Hours of Sleep Calculator

Written by SleepCalculator Editorial TeamLast checked August 2026

Sources:CDC - About Sleep Sleep Foundation - Stages of Sleep AASM/SRS - Recommended Sleep Duration

Hours of sleep calculator

Enter both ends of the night to see the real total and where your alarm lands.

Time you get into bed

Time your alarm goes off

Time in bed

Actual sleep

Minus ~15 min to fall asleep

7h 45m

Complete cycles

plus 15m into cycle 6

Distance from a cycle boundary

Adjustable

15m

You wake 15m into a new cycle. Going to bed 15m later, or waking 15m earlier, lands you on the boundary.

Two times in, one number out. The part most calculators skip is the third line: how far your alarm lands from a cycle boundary, and which direction to move it. A 15-minute change often does more for how you feel than an extra 45 minutes in bed.

Time in bed is not sleep

The gap is bigger than people expect. A healthy sleeper takes 10 to 20 minutes to fall asleep and wakes briefly several times a night without remembering it. Eight hours between lights out and the alarm is usually somewhere between 7 and 7.5 hours of actual sleep. Any honest calculation has to subtract that, which is why the tool above does.

What each total buys you

What each nightly total buys you
Time asleep	Cycles	Realistic verdict
4h 30m	3	Emergency only. Measurable impairment the next day.
6h 00m	4	Below the adult range. Sustainable for a week, not a season.
7h 30m	5	The realistic weekday target for most adults.
9h 00m	6	Full recovery. What you want after hard training, illness, or a debt.

Common bedtime and wake-up pairs

The exact numbers for the combinations people look up most:

If the total is short every night

Adding hours to the schedule is the obvious fix and the one that usually fails, because the missing time is not available. The two that work are moving the wake-up time later where the job allows, and cutting the gap between time in bed and time asleep. The second is free. Run a week through the sleep efficiency calculator and see how much of your night you are losing before you assume you need more of it.

Related: how much sleep you need by age, and the sleep cycle calculator for aligning the alarm.