Sleep & wake-up
Hours of sleep calculator
Enter your bedtime and wake-up time to see how many hours of sleep you get and how many cycles that covers.
Most adults do best on 7–9 hours. The time between your bedtime and alarm is time in bed, not true sleep, so count on losing a little to falling asleep and brief wakings.
How much sleep are you really getting?
It is easy to assume you sleep plenty, but the gap between lights-out and your alarm is often smaller than you think. This calculator takes your bedtime and wake time and shows the total in hours and minutes, then converts it to roughly 90-minute sleep cycles. Waking at the end of a cycle, rather than the middle, tends to feel easier because you are in lighter sleep.
| Hours in bed | How it tends to feel |
|---|---|
| Under 6 | Short; alertness and mood usually suffer |
| 6 to 7 | Borderline; fine occasionally, risky as a habit |
| 7 to 9 | The range most adults function best on |
Closing the gap
Time in bed is not the same as time asleep. Most people need 10 to 20 minutes to drift off and wake briefly once or twice in the night, so your real sleep total runs a little under the figure here. If the number looks low, the simplest fix is usually an earlier, more consistent bedtime rather than a later alarm. Keep your wake time steady even at weekends; a stable rhythm makes falling asleep faster and the hours you do get more restorative.
Frequently asked questions
How many hours of sleep do I need?
Most adults do best on 7 to 9 hours. Teenagers need more, around 8 to 10, and needs shift with age. Judge it by how alert you feel through the day, not just the clock.
Does time in bed equal time asleep?
No. This tool measures the span between bedtime and wake time. Your actual sleep is usually a bit less, since it takes time to fall asleep and most people wake briefly overnight.
What are 90-minute sleep cycles?
Sleep moves through cycles of roughly 90 minutes, from light to deep to dream sleep. Waking at the end of a cycle often feels easier than being pulled out of deep sleep mid-cycle.