Bedtime & Sleep Cycle Calculator
Find Your Perfect Bedtime & Feel Energized Tomorrow
The smartest sleep calculator — personalized for real life.
Calculate My Bedtime- · No sign-up
- · No data stored
- · Works offline
- Built on real cycles90-min REM & deep sleep math
- Personalized to youcaffeine, kids, jet lag, age
- Energy forecastknow how tomorrow will feel
- 100% privatenothing leaves your device
Your sleep details
We use your real-world factors to predict the best bedtime tonight.
🌙 Lights out by
- 9:46 PM In bed
- 10:00 PM Asleep · 14 min
- 7:00 AM Wake refreshed
Tomorrow's Energy Score
Sleep cycles
Each bar = one 90-minute cycle of light, deep & REM sleep.
Personalized tips
How it works
Built around the 90-minute sleep cycle
Your brain doesn't sleep flat. It rolls through 4–6 cycles of light, deep, and REM sleep — each about 90 minutes. Wake up at the end of a cycle and you'll feel sharp. Wake up mid-cycle and you'll feel groggy, no matter how long you slept.
Most calculators stop there. Dozely also factors in the things that actually mess with your night: caffeine, kids, shift work, jet lag, and how wired you feel right now.
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1
Pick your wake time
We work backward from when you actually need to be up.
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2
Tell us about your day
Age, energy, caffeine, kids, shift work, travel — all change the math.
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Get your bedtime + energy score
Two ideal options, a fall-asleep buffer, and tomorrow's energy forecast.
Quick reference
What time should I go to bed by wake-up time?
A handy lookup if you don't want to use the full calculator. All times are when to be in bed — they already include the typical 14-minute fall-asleep window.
| Wake at | Bedtime · 6 cycles 9 hours sleep |
Bedtime · 5 cycles 7.5 hours sleep |
Bedtime · 4 cycles 6 hours sleep |
|---|---|---|---|
| 5:00 AM | 7:46 PM | 9:16 PM | 10:46 PM |
| 5:30 AM | 8:16 PM | 9:46 PM | 11:16 PM |
| 6:00 AM | 8:46 PM | 10:16 PM | 11:46 PM |
| 6:30 AM | 9:16 PM | 10:46 PM | 12:16 AM |
| 7:00 AM | 9:46 PM | 11:16 PM | 12:46 AM |
| 7:30 AM | 10:16 PM | 11:46 PM | 1:16 AM |
| 8:00 AM | 10:46 PM | 12:16 AM | 1:46 AM |
| 8:30 AM | 11:16 PM | 12:46 AM | 2:16 AM |
| 9:00 AM | 11:46 PM | 1:16 AM | 2:46 AM |
Want a personalized answer that accounts for caffeine, kids, shift work, or jet lag? Use the full calculator above ↑
How much sleep
How many hours of sleep do you need by age?
Based on guidance from the National Sleep Foundation and the American Academy of Sleep Medicine.
| Age group | Recommended sleep | Cycles per night |
|---|---|---|
| Newborns (0–3 mo) | 14 – 17 hours | 9 – 11 |
| Infants (4–11 mo) | 12 – 15 hours | 8 – 10 |
| Toddlers (1–2 yr) | 11 – 14 hours | 7 – 9 |
| Preschool (3–5 yr) | 10 – 13 hours | 6 – 8 |
| School age (6–13 yr) | 9 – 11 hours | 6 – 7 |
| Teens (14–17 yr) | 8 – 10 hours | 5 – 6 |
| Adults (18–64 yr) | 7 – 9 hours | 5 – 6 |
| Older adults (65+) | 7 – 8 hours | 5 |
Frequently asked questions
What time should I go to bed if I want to wake up at 7 AM?
To wake up refreshed at 7:00 AM, be in bed by 9:46 PM for 6 full sleep cycles (9 hours) or 11:16 PM for 5 cycles (7.5 hours). Both options already account for the ~14 minutes it usually takes to fall asleep — so you'll be in deep sleep right on schedule.
How long is one sleep cycle?
A full sleep cycle averages around 90 minutes and includes light, deep, and REM stages. Waking at the end of a cycle leaves you feeling more energized than waking mid-cycle.
Is the bedtime calculator free?
Yes. It's 100% free, requires no account, and stores no personal data. Everything runs in your browser.
How many hours of sleep do I really need?
Most adults do best on 7–9 hours. Teens need 8–10. Sleeping in full 90-minute cycles is why 7.5 or 9 hours often feels better than a flat 8.
What time should I go to bed if I want to wake up at 6 AM?
To wake up at 6:00 AM, be in bed by 8:46 PM for 6 cycles (9 hours) or 10:16 PM for 5 cycles (7.5 hours). For a shorter night, 11:46 PM gives 4 cycles (6 hours). See the full reference table for other wake times.
Why do I wake up tired even after 8 hours of sleep?
If your alarm fires mid-cycle — especially during deep sleep — you'll feel groggy no matter how long you slept. That's sleep inertia. Aiming for full 90-minute cycles (7.5 or 9 hours) usually feels better than a flat 8 hours, because you wake during light sleep instead of deep sleep.
How long does it take to fall asleep?
The average healthy adult falls asleep in 10–20 minutes (called sleep latency). Caffeine, stress, screens, and jet lag can push that to 30+ minutes. Falling asleep in under 5 minutes can actually be a sign of sleep deprivation.
Is it better to sleep 6 or 7.5 hours?
7.5 hours is almost always better. It gives you 5 complete sleep cycles — including the REM-heavy ones in the second half of the night that consolidate memory and mood. 6 hours (4 cycles) is the bare minimum and skips most of your final REM cycle.