Use this free sleep calculator to find the best bedtime or wake-up time based on 90-minute sleep cycles, sleep duration, and time to fall asleep.
Sleep Calculator: Find Your Best Bedtime & Wake-Up Time
Use this free sleep calculator to plan when to sleep or when to wake up based on common 90-minute sleep cycles, your target sleep duration, and the time you usually need to fall asleep.
Sleep Calculator
Choose a mode, enter your time, and get suggested sleep-cycle times instantly.
Suggested bedtimes
Based on 90-minute cyclesTip: These are planning estimates. Real sleep cycles vary from person to person.
How this sleep calculator works
This calculator uses a simple 90-minute sleep-cycle estimate. When you enter a wake-up time, it counts backward by several sleep cycles and subtracts your fall-asleep time. When you enter a bedtime, it counts forward by several sleep cycles and adds your fall-asleep time.
Sleep-cycle reference table
| Sleep cycles | Approximate sleep time | Common use case |
|---|---|---|
| 6 cycles | About 9 hours | Longer full-night sleep |
| 5 cycles | About 7.5 hours | Common adult sleep target |
| 4 cycles | About 6 hours | Shorter night when needed |
| 3 cycles | About 4.5 hours | Very short sleep, not ideal long term |
What is the best time to sleep?
The best time to sleep depends on your wake-up time and your sleep need. For example, if you need to wake up at 7:00 AM and usually take 15 minutes to fall asleep, the calculator may suggest several bedtime options such as around 9:45 PM, 11:15 PM, 12:45 AM, or 2:15 AM depending on the number of sleep cycles.
What is the best time to wake up?
If you already know your bedtime, use the wake-up mode. The calculator will estimate wake-up times after 3, 4, 5, or 6 sleep cycles. Many people prefer waking near the end of a cycle rather than during deeper sleep, although real sleep patterns can vary.
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Sleep calculator FAQ
Common questions about bedtime, wake-up time, and sleep-cycle planning.
What time should I go to bed if I wake up at 7 AM?
If you wake up at 7 AM and take about 15 minutes to fall asleep, possible bedtime options include about 9:45 PM for 6 cycles, 11:15 PM for 5 cycles, and 12:45 AM for 4 cycles.
Is 90 minutes always one sleep cycle?
No. 90 minutes is a common average used for simple sleep planning. Real sleep cycles vary by person and by night.
Is waking up at the end of a sleep cycle better?
Many people feel less groggy when waking closer to the end of a sleep cycle, but sleep quality, total sleep time, stress, and health also matter.
How many sleep cycles should adults aim for?
Many adults plan around 5 to 6 cycles, which is roughly 7.5 to 9 hours of sleep. Some people need more or less.
Can this calculator fix insomnia?
No. This calculator only helps with schedule planning. If you have ongoing insomnia or serious sleep issues, speak with a qualified health professional.