Sleep Cycle Calculator
Find your ideal bedtime for any wake-up time — or the ideal wake time for any bedtime — using 90-minute sleep cycles and a 14-minute fall-asleep buffer.
Sleep Cycle Calculator
Enter your numbers below and hit Calculate — the answer appears instantly, computed entirely in your browser.
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What is Sleep cycle calculator?
Sleep Cycle Calculator — Find your ideal bedtime for any wake-up time — or the ideal wake time for any bedtime — using 90-minute sleep cycles and a 14-minute fall-asleep buffer.
The engine is the open-source sleepcycle.tools calculator (MIT), which uses the widely cited averages of 90-minute sleep cycles and a 14-minute sleep-onset (fall-asleep) buffer. For a wake-up time, each bedtime is computed as wake time minus (cycles × 90 + 14) minutes, for 5 down to 1 cycles; for a bedtime the same formula is applied forward. Options totaling 7.5 hours (5 cycles) are marked Recommended and 6 hours (4 cycles) Good, matching the engine's healthy-range guidance. These are population averages — real cycles vary between roughly 70 and 120 minutes per person, and the calculator cannot account for insomnia, sleep disorders, caffeine, or age. It is general wellness guidance, not medical advice.
Why use this sleep cycle calculator?
Built for sleep cycle calculator
Find your ideal bedtime for any wake-up time — or the ideal wake time for any bedtime — using 90-minute sleep cycles and a 14-minute fall-asleep buffer.
Transparent & honest
Uses the engine's fixed averages: 90-minute cycles and a 14-minute fall-asleep buffer. Real cycles vary (~70–120 minutes) and onset latency varies by person and night.
Private by design
Everything runs in your browser. Your inputs never leave your device.
Works everywhere
Fully responsive — perfect on desktop, tablet, and mobile. No app needed.
Regularly updated
Regularly maintained and reviewed to ensure accuracy.
Free forever
No accounts, no limits, no watermarks. Use Sleep Cycle Calculator as much as you need.
How to use Sleep Cycle Calculator
- 1Tell the tool what you know: pick "Wake-up time" if your alarm is fixed, or "Bedtime" if your lights-out time is fixed.
- 2Enter the time in 24-hour format — for example 06:30 for a 6:30 AM alarm, or 23:00 for an 11 PM bedtime.
- 3Run the tool to get five options, from 5 complete sleep cycles down to 1, each with total hours of sleep.
- 4Prefer the options marked Recommended (5 cycles, 7.5 hours) or Good (4 cycles, 6 hours) — they land in the healthy 6–9 hour range.
- 5Set your alarm for the chosen time so you wake at the end of a cycle, when sleep is lightest and grogginess is lowest.
What can you do with Sleep Cycle Calculator?
- What time should i go to sleep — Find your ideal bedtime for any wake-up time — or the ideal wake time for any bedtime — using 90-minute sleep cycles and a 14-minute fall-asleep buffer.
- Sleep cycle chart — Find your ideal bedtime for any wake-up time — or the ideal wake time for any bedtime — using 90-minute sleep cycles and a 14-minute fall-asleep buffer.
- Best time to wake up — Find your ideal bedtime for any wake-up time — or the ideal wake time for any bedtime — using 90-minute sleep cycles and a 14-minute fall-asleep buffer.
- How many sleep cycles do i need — Find your ideal bedtime for any wake-up time — or the ideal wake time for any bedtime — using 90-minute sleep cycles and a 14-minute fall-asleep buffer.
- 90 minute sleep cycle calculator — Find your ideal bedtime for any wake-up time — or the ideal wake time for any bedtime — using 90-minute sleep cycles and a 14-minute fall-asleep buffer.
- Bedtime calculator for adults — Find your ideal bedtime for any wake-up time — or the ideal wake time for any bedtime — using 90-minute sleep cycles and a 14-minute fall-asleep buffer.
Good to know
- Uses the engine's fixed averages: 90-minute cycles and a 14-minute fall-asleep buffer. Real cycles vary (~70–120 minutes) and onset latency varies by person and night.
- Bedtime means the time you fall asleep, not the time you get into bed — allow extra wind-down time beyond the 14-minute buffer.
- General wellness guidance only: it cannot diagnose or treat insomnia, sleep apnea, or other sleep disorders — talk to a clinician for persistent sleep problems.
How it works
The engine is the open-source sleepcycle.tools calculator (MIT), which uses the widely cited averages of 90-minute sleep cycles and a 14-minute sleep-onset (fall-asleep) buffer. For a wake-up time, each bedtime is computed as wake time minus (cycles × 90 + 14) minutes, for 5 down to 1 cycles; for a bedtime the same formula is applied forward. Options totaling 7.5 hours (5 cycles) are marked Recommended and 6 hours (4 cycles) Good, matching the engine's healthy-range guidance. These are population averages — real cycles vary between roughly 70 and 120 minutes per person, and the calculator cannot account for insomnia, sleep disorders, caffeine, or age. It is general wellness guidance, not medical advice.
Examples
Bedtime options: 10:46 PM (5 cycles, Recommended), 9:16 PM … down to 4:46 AM (1 cycle).
Wake options: 6:44 AM (5 cycles, Recommended), 8:14 AM … each at the end of a full cycle.
If a full night is impossible, the 4-cycle option (12:46 AM, 6 hours, Good) beats an interrupted 5-cycle attempt.
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