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Sleep Calculator
How much sleep do you get, and is it enough for your age? Plus the best bedtimes and wake-up times for full 90-minute sleep cycles.
Most adults need at least seven hours of sleep a night, yet many get less. This calculator shows how much sleep you get between your bedtime and wake-up time — including across midnight — after allowing for the time it takes to fall asleep, and compares it with the hours recommended for your age group.
It also helps you plan. Sleep runs in cycles of roughly 90 minutes, and waking at the end of a cycle often feels easier than being woken in the middle of deep sleep. So the calculator lists the bedtimes that fit four, five or six full cycles before your alarm, and the wake-up times that fit them after you go to bed. Nothing you enter is stored or sent.
How to use Sleep Calculator
- Enter your bedtime and wake-up time.
- Enter how long it usually takes you to fall asleep.
- Choose your age group.
- Read your sleep time and the suggested bedtimes and wake-up times.
Features
- Sleep duration across midnight.
- Allows for the time to fall asleep.
- Recommended hours for seven age groups.
- Bedtimes for a wake-up time, in full sleep cycles.
- Wake-up times for a bedtime, in full sleep cycles.
- Runs in your browser; nothing is stored or sent.
How much sleep you need
The American Academy of Sleep Medicine and the US Centers for Disease Control and Prevention publish these recommendations for each 24 hours, including naps for young children. Needs vary from person to person, but regularly getting less than the lower figure is linked with poorer concentration, mood, immunity and long-term health.
| Age group | Recommended sleep |
|---|---|
| Toddlers, 1–2 years | 11–14 hours |
| Preschool, 3–5 years | 10–13 hours |
| School age, 6–12 years | 9–12 hours |
| Teens, 13–17 years | 8–10 hours |
| Adults, 18–60 years | 7 or more hours |
| Adults, 61–64 years | 7–9 hours |
| Adults, 65 and over | 7–8 hours |
Sleep cycles
During the night you move through cycles of light sleep, deep sleep and REM (dreaming) sleep. Each cycle lasts roughly 90 minutes, though anywhere from 70 to 120 minutes is normal and cycles change through the night. Being woken from deep sleep can leave you groggy for a while, so timing your alarm for the end of a cycle may help you wake more easily. Five cycles is about seven and a half hours, six cycles nine hours. The suggestions add the time you take to fall asleep — about 15 minutes for most people. Treat them as a guide; total sleep matters more than hitting a cycle exactly.
Duration is not quality
This calculator measures how long you sleep, not how well. Frequent waking, loud snoring, pauses in breathing, restless legs, or feeling exhausted despite enough hours can be signs of a sleep disorder such as sleep apnoea or insomnia, which are common and treatable. If any of these sound familiar, or poor sleep affects your daily life for weeks, talk to a doctor.
Tips for better sleep
Keep the same bedtime and wake-up time every day, including weekends. Get daylight in the morning and keep the bedroom dark, quiet and cool. Avoid caffeine in the afternoon and large meals and alcohol close to bedtime. Put screens away for the last half hour, and if you cannot sleep after about 20 minutes, get up and do something calm until you feel sleepy. Regular exercise helps too, as long as hard sessions finish a few hours before bed. Short naps of 20 to 30 minutes early in the afternoon can top up sleep without spoiling the night.
Frequently asked questions
How much sleep do I need?
Adults need at least 7 hours; teenagers 8–10; school-age children 9–12.
What time should I go to bed?
Count back from your wake-up time by whole 90-minute cycles plus the time you take to fall asleep. The calculator lists the options.
How long is a sleep cycle?
About 90 minutes on average, between 70 and 120 minutes.
Does the calculator handle bedtimes after midnight?
Yes. Any bedtime and wake-up time works, across midnight or not.
Does this measure sleep quality?
No. It only measures duration; see a doctor about poor-quality sleep.
Can I catch up on sleep at the weekend?
Sleeping in helps a little, but a regular schedule with enough sleep every night works better than catching up.
Is my data stored?
No. Everything is calculated in your browser.
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