Sleeping calculator Use 90-minute sleep cycles plus your age to find optimal times. No signup, no ads.
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🛏️ What time should I go to sleep tonight?
We calculate your ideal bedtime tonight from your last wake-up + age-based sleep need.
🌅 What time should I wake up?
We calculate the best wake-up times that land at the end of a 90-min cycle.
How it works
Your brain runs 90-minute sleep cycles through light sleep, deep sleep, and REM. Waking between cycles feels effortless. Waking mid-cycle — especially in deep sleep — leaves you groggy for up to an hour (sleep inertia).
We also add a 15-minute fall-asleep buffer, the average sleep latency for healthy adults.
Sleep needs by age
| Age | Recommended | Cycles |
|---|---|---|
| Toddlers 1–2 | 11–14 hours | consult pediatrician |
| Children 3–5 | 10–13 hours | 7–8 |
| Children 6–12 | 9–11 hours | 6–7 |
| Teens 13–17 | 9–10.5 hours | 6–7 |
| Adults 18–64 | 7–9 hours | 5–6 |
| Older adults 65+ | ~7.5 hours | 5 |
Source: CDC · American Academy of Sleep Medicine
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Medical disclaimer. Everything on this page is general educational information and is not a substitute for professional medical advice. Sleep needs vary from person to person. If you have ongoing sleep problems, talk to a licensed healthcare professional.