Sleep Cycle Calculator
Bedtimes and wake-up times by number of sleep cycles
Runs in your browser · nothing is uploaded
Updated 2026-10-04The values in the form (wake-up 07:00, 90-minute cycles, 15 minutes to fall asleep) are just an example. Change them to fit your routine.
What to calculate
70-120 minutes. 90 is a commonly used average, and it differs from person to person.
0-60 minutes. 15 is an example. Use how long it really takes you to drop off after lying down.
5 cycles: 23:15 (previous day)
Result
Get into bed at one of these times to wake at 07:00
| Cycles | Get into bed | Sleep | Time in bed |
|---|---|---|---|
| 3 cycles | 02:15 | 4 h 30 min | 4 h 45 min |
| 4 cycles | 00:45 | 6 h 0 min | 6 h 15 min |
| 5 cycles | 23:15previous day | 7 h 30 min7 h or more | 7 h 45 min |
| 6 cycles | 21:45previous day | 9 h 0 min7 h or more | 9 h 15 min |
The mark follows the AASM and Sleep Research Society consensus statement (Watson NF et al., Sleep 2015;38(6):843-844) that adults should sleep 7 or more hours a night. It does not say how many cycles are right.
The math with your numbers
- 3 cycles: 07:00 - (3 x 90 min + 15 min) = 02:15
- 4 cycles: 07:00 - (4 x 90 min + 15 min) = 00:45
- 5 cycles: 07:00 - (5 x 90 min + 15 min) = 23:15 (previous day)
- 6 cycles: 07:00 - (6 x 90 min + 15 min) = 21:45 (previous day)
This is a rough estimate for reference. It does not diagnose or treat anything. If you stay tired despite sleeping, or snoring or insomnia lasts, talk to a doctor. Cycle length and time to fall asleep differ between people and between nights, so the times are only a guide. Sleep time counts the time asleep, not the time in bed.
Source: Watson NF et al., "Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society", Sleep 2015;38(6):843-844 (adults: 7 or more hours a night). The 90-minute cycle is a commonly used average, so you can change it. Retrieved 2026-10-04.
What it is
The sleep cycle calculator works backwards from the time you must get up to suggest when to get into bed, or forwards from a bedtime or from right now to show when you could wake. It lists four options, from 3 to 6 cycles, marks times that fall on the previous or next day, and flags options with 7 hours of sleep or more. The form opens with an example (wake-up 07:00, 90-minute cycles, 15 minutes to fall asleep) so a result shows at once. Everything is computed in your browser.
How to use
- Pick what to calculate: a bedtime for a wake-up time, a wake-up time for a bedtime, or the wake-up times if you fall asleep now.
- Enter the time. The now option reads your device’s clock.
- Adjust the cycle length and the time to fall asleep to match you.
- Read the table for the time, hours of sleep and time in bed for each cycle count.
- Check the math lines below to see how each time was reached.
How it works
- Bedtime for a wake-up time = wake-up time - (cycles x cycle length + time to fall asleep).
- Wake-up time for a bedtime = bedtime + time to fall asleep + cycles x cycle length.
- The options are 3, 4, 5 and 6 cycles. Sleep time is cycles x cycle length and does not include the time to fall asleep.
- Cycle length takes whole minutes from 70 to 120, and time to fall asleep from 0 to 60. The defaults of 90 and 15 are examples.
- The 7 hours or more mark appears when sleep is at least 420 minutes. It follows Watson NF et al., Recommended Amount of Sleep for a Healthy Adult (AASM and Sleep Research Society consensus statement), Sleep 2015;38(6):843-844, which says adults should sleep 7 or more hours a night.
- A time that crosses midnight is labelled previous day or next day relative to the time you entered. Exactly 00:00 counts as the same day.
- Retrieved 2026-10-04.
Examples
Wake-up 07:00, 90-minute cycles, 15 minutes to fall asleep.
| Cycles | Math | Bedtime | Sleep |
|---|---|---|---|
| 3 | 07:00 - (270 + 15) min | 02:15 | 4 h 30 min |
| 4 | 07:00 - (360 + 15) min | 00:45 | 6 h 0 min |
| 5 | 07:00 - (450 + 15) min | 23:15 (previous day) | 7 h 30 min, 7 h or more |
| 6 | 07:00 - (540 + 15) min | 21:45 (previous day) | 9 h 0 min, 7 h or more |
Good to know
This is a rough estimate for reference. It does not diagnose or treat anything. If you stay tired despite sleeping, or snoring or insomnia lasts, talk to a doctor. Cycle length and time to fall asleep vary, so the times are only a guide. A regular schedule, with similar sleep and wake times every day, often matters more than hitting an exact minute.
FAQ
How does the sleep cycle calculator work?
For a wake-up time it subtracts the number of cycles times the cycle length, plus the time you need to fall asleep, to give a bedtime. For a bedtime it adds the same amounts to give a wake-up time.
Is a sleep cycle always 90 minutes?
No. 90 minutes is a commonly used average and it differs between people and between nights, so you can set any whole number from 70 to 120 minutes.
How many cycles should I sleep?
The calculator does not say. The 7 hours or more mark follows the AASM and Sleep Research Society consensus statement for adults (Watson NF et al., Sleep 2015). It is not a recommendation of a cycle count.
Why is there a time to fall asleep?
Most people do not fall asleep the moment they lie down. 15 minutes is an example, so use how long it really takes you.
What does If I fall asleep now use?
It reads your device's current time and treats it as the time you get into bed. The time stays on your device and is sent nowhere.
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