How Much Sleep Do I Need? Sleep Need Calculator by Age

Most adults need 7 to 9 hours of sleep a night, teenagers need about 8 to 10, and adults over 65 usually do well on 7 to 8 ^[1]. Enter your age and the calculator shows the ranges from the main sleep organizations. Tell it how long you sleep now and how you feel during the day, and it suggests a personal starting target plus the bedtime that goes with your alarm.

Recommended sleep by age

The numbers most health sites quote come from two sets of expert panels. The National Sleep Foundation's panel reviewed the research and agreed on ranges for every age group ^[1], from 9 to 11 hours for school-age kids up to 13, to 7 to 8 hours from 65 ^[8]. The American Academy of Sleep Medicine set 8 to 10 hours for teens aged 13 to 18 ^[7] and, with the Sleep Research Society, a floor of 7 hours or more for adults ^[3]. The NIH's National Heart, Lung, and Blood Institute uses the same 8 to 10 hours for teens ^[2]. The groups mostly agree. Where they split is at the edges of the teenage years:

The calculator starts at 13. Younger children need more sleep, and the right amount changes quickly with age, so that is a conversation for your pediatrician.

How the calculator picks your starting target

A range is an answer for a whole population. To turn it into a number for you, the calculator uses three simple rules. They are our own rules of thumb, built on the research below, not an official formula.

• You feel alert, already sleep within the range and don't sleep much longer on free nights. Your current work-night amount becomes the target, rounded to the nearest 15 minutes. If it is working, why change it?
• You feel sleepy in the day and sleep more than an hour longer on free nights. That combination suggests you are running short, so the target is the middle of the range plus 30 minutes, capped at the top of the range.
• Anything else. The target is the middle of the range: 9 hours for teens, 8 for adults up to 64, 7 hours 30 minutes from 65.

The bedtime is your wake time minus the target minus 15 minutes to fall asleep. For bedtimes that also line up with sleep cycles, use the sleep calculator.

Worked example

Maya is 30 and gets up at 7:00 AM. On work nights she sleeps about 6 hours 30 minutes; on weekends, with no alarm, about 8 hours. She feels fine most days.

• Her range is 7 to 9 hours, so her work nights fall below it.
• Her weekend catch-up is 1 hour 30 minutes, but she doesn't feel sleepy, so neither of the first two rules applies and the calculator uses the middle of the range: 8 hours.
• Lights out: 7:00 AM minus 8 hours minus 15 minutes = 10:45 PM. That is 1 hour 30 minutes more sleep than she gets now.

If Maya often felt sleepy in the day too, the target would rise to 8 hours 30 minutes, with lights out at 10:15 PM.

Why the answer is a range, not one number

Sleep need is partly personal. The National Sleep Foundation's panel stressed that requirements vary from person to person, and that sleeping a little outside the range may be fine, while straying far outside it is rare ^[1]. A neat lab study from Japan shows how wide the spread can be. Fifteen healthy young men were given 12 hours in bed every night for nine nights. As their hidden sleep debt was paid off, their sleep tapered toward a personal level that ranged from about 7.3 to 9.3 hours, with an average of 8.4 ^[6]. At home the same men had averaged about 7.4 hours, roughly an hour less than they seemed to need, and none of them thought they had a sleep problem ^[6].

The two-week self-test

You can run a rough version of that experiment at home, ideally on vacation. Go to bed when you feel sleepy, let yourself wake without an alarm, and note how long you sleep each night. Expect the first few nights to run long while you pay back debt. In the lab, even one hour of hidden debt took about four days to recover, and sleep time then tapered off and leveled out ^[6]. Where your own nights settle, together with how you feel during the day, is a reasonable estimate of your need. If you cannot take time off, try the calculator's target for two weeks and adjust by 15 to 30 minutes either way.

Signs you are not getting enough

A few honest questions help here. Do you lean on caffeine to stay focused? Do you doze off on the couch or in meetings without meaning to ^[4]? When you finally get the chance, do you sleep far longer than usual ^[6]? A yes to any of these suggests you need more sleep than you are getting now. If you are regularly under 7 hours, read whether 6 hours of sleep is enough, and if the shortfall has been building for a while, the sleep debt calculator can put a number on it.

Limits and when to see a doctor

The ranges are for healthy people without a sleep disorder ^[1]. They do not adjust for pregnancy or shift work, and you may need more than usual for a while when you are ill or recovering from a run of short nights ^[2]. The calculator also takes your self-report at face value, and people are not always good judges of their own sleep.

Talk to a doctor if you sleep the recommended amount but still feel sleepy in the day, if you regularly need far more than 9 or 10 hours, or if you snore loudly or someone notices pauses in your breathing. People who habitually sleep well outside the normal range may be showing signs of a health problem ^[1]. Sleepiness that affects your safety, like nodding off at the wheel, needs attention promptly.