Sleep Calculator
Find suggested bedtimes for when you need to wake up -- or wake-up times for when you go to bed -- based on approximate 90-minute sleep cycles and the time it takes you to fall asleep.
Plan your sleep
Health note: This is an everyday planning tool, not a medical or diagnostic tool. Sleep cycles vary between people and through the night. If you regularly have trouble sleeping, snore loudly, stop breathing during sleep or feel very sleepy during the day, talk to a doctor.
Results
Highlighted times give 5 or more cycles (7.5 hours or more), in line with general guidance of at least 7 hours for adults.
Recommended sleep by age (reference)
| Age group | General recommendation (per 24 hours) |
|---|---|
| Infants 4–12 months | 12–16 hours, including naps |
| Children 1–2 years | 11–14 hours, including naps |
| Children 3–5 years | 10–13 hours, including naps |
| Children 6–12 years | 9–12 hours |
| Teenagers 13–18 years | 8–10 hours |
| Adults 18–60 years | 7 or more hours |
| Adults 61–64 years | 7–9 hours |
| Adults 65+ years | 7–8 hours |
Based on published general guidance (American Academy of Sleep Medicine / US CDC). Individual needs vary; this is informational only.
How this calculator works
A typical night is made up of several sleep cycles lasting roughly 90 minutes each on average. For a wake-up time, the calculator counts back 6, 5, 4 and 3 cycles plus the minutes you usually take to fall asleep; for a bedtime, it counts forward the same way. If you set a duration target, it also shows the exact bedtime or wake-up time for that amount of sleep. Times wrap past midnight automatically.
Is a sleep cycle always 90 minutes?
No. A sleep cycle is roughly 90 minutes on average, but it typically ranges from about 70 to 120 minutes and changes through the night and from person to person. The times shown are approximate suggestions, not precise predictions.
Will waking up at the end of a cycle guarantee I feel rested?
No. Timing your alarm around sleep cycles may help some people wake during lighter sleep, but it doesn't guarantee better sleep. Getting enough total sleep regularly, and keeping a consistent schedule, matter more.
How much sleep do I need?
General guidance for adults is at least 7 hours a night. Children and teenagers need more. Individual needs vary -- the reference table on this page is informational only.
Is my data stored?
No. The times you enter are used only in your browser and are not saved, sent to our servers or included in analytics.
Disclaimer: This tool is for general information only and is not medical advice, diagnosis or treatment. See our Disclaimer and Terms of Use for more detail.