How to use it
- Enter your age in years or months.
- Choose whether you know your wake-up time or your bedtime.
- Enter the time and how long it takes you to fall asleep.
- Pick one of the suggested times.
How much sleep you need by age
The calculator shows the recommendations of the National Sleep Foundation (NSF) and the American Academy of Sleep Medicine (AASM):
| Age | NSF | AASM |
|---|---|---|
| Newborn (0–3 months) | 14–17 h | no separate recommendation |
| Infant (4–11 months) | 12–15 h | 12–16 h |
| Toddler (1–2 years) | 11–14 h | 11–14 h |
| Preschool (3–5 years) | 10–13 h | 10–13 h |
| School age (6–12 years) | 9–11 h | 9–12 h |
| Teen (13–17 years) | 8–10 h | 8–10 h |
| Adult (18–64) | 7–9 h | 7 h or more |
| Older adult (65+) | 7–8 h | 7 h or more |
For babies and young children, naps count toward the total.
How the bedtime calculator works
Sleep runs in cycles of light sleep, deep sleep and REM sleep, each lasting roughly 90 minutes. Waking at the end of a cycle, rather than in deep sleep, may help you feel less groggy.
The calculator adds (or subtracts) whole 90-minute cycles plus the time it takes you to fall asleep (15 minutes by default):
Bedtime = wake-up time − falling-asleep time − cycles × 90 min
Example: you want to wake at 6:30 AM and take 15 minutes to fall asleep. Six cycles (9 hours) means lights out at 9:15 PM; five cycles (7.5 hours) at 10:45 PM; four cycles (6 hours) at 12:15 AM. Options that fall within the recommended hours for your age are highlighted.
Treat cycles as a rule of thumb
Real sleep cycles vary from about 70 to 120 minutes and change through the night, so no calculator can time your cycles exactly. Getting enough total sleep and keeping a regular schedule, including on weekends, matter more than hitting a precise minute.
Tips for better sleep
- Keep the same bedtime and wake-up time every day.
- Get daylight in the morning and dim the lights in the evening.
- Avoid caffeine in the afternoon and heavy meals or alcohol close to bedtime.
- Keep your bedroom cool, dark and quiet, and put screens away 30–60 minutes before bed.
- If you can't fall asleep after about 20 minutes, get up and do something calm until you feel sleepy.
When to see a doctor
Talk to your doctor if you regularly struggle to fall or stay asleep, snore loudly or stop breathing during sleep, feel very sleepy during the day despite enough time in bed, or fall asleep at inappropriate times. These can be signs of insomnia, sleep apnea or other treatable conditions.
This calculator is informational and not medical advice. Everything runs in your browser.
Frequently asked questions
How many hours of sleep do adults need?
Most adults need at least 7 hours a night. The National Sleep Foundation recommends 7–9 hours for ages 18–64 and 7–8 hours for 65 and older.
What time should I go to bed to wake up at 6 AM?
For 7.5 hours of sleep (five cycles) plus 15 minutes to fall asleep, go to bed at 10:15 PM. For 9 hours, at 8:45 PM.
How long is a sleep cycle?
About 90 minutes on average, but it ranges from roughly 70 to 120 minutes and varies through the night.
How much sleep do teenagers need?
8–10 hours a night, according to both the NSF and the AASM.
Is 6 hours of sleep enough?
For most adults, regularly sleeping 6 hours or less is not enough and is linked to health risks.
Sources
- NHLBI: How much sleep is enough?
- Watson NF et al.: Recommended Amount of Sleep for a Healthy Adult, AASM and SRS consensus (2015)
- Paruthi S et al.: Recommended Amount of Sleep for Pediatric Populations, AASM consensus (J Clin Sleep Med, 2016)
Last reviewed: November 14, 2026 · Kitpebble editorial team
Change log
- : Sources expanded; FAQ and content reviewed.
- : Sources expanded; FAQ and content reviewed.
For general information only; not medical advice or a diagnosis. How we write and review our pages