Sleep Cycle Calculator
Get recommended times based on sleep cycles for better wake-ups.
What is Sleep Cycle Calculator
Time your sleep around ~90-minute cycles — the loop through light sleep, deep sleep and REM. Enter your alarm time to get ideal bedtimes, or choose "if I sleep now" for wake-up options; results cover 4, 5 and 6 cycles with the recommended ones highlighted and a 15-minute fall-asleep buffer already included.
How to use Sleep Cycle Calculator
- Choose "I want to wake up at" or "If I sleep now"
- Set your target time
- Pick one of the 4/5/6 suggested cycle times
- Prefer the highlighted recommended option
Frequently asked questions
Why 90-minute cycles?
Sleep loops through light sleep, deep sleep and REM roughly every 90 minutes. Waking at the end of a cycle — during light sleep — feels far better than being woken mid-cycle.
What is the 15-minute buffer?
Most people need about 15 minutes to actually fall asleep after lying down, so it is already included in the bedtime results.
How many cycles should I aim for?
Most adults do best with 5–6 cycles (about 7.5–9 hours); 4 cycles (~6 hours) is fine only occasionally. The page shows 4/5/6-cycle times side by side with the recommendation highlighted.
Will this guarantee I wake up refreshed?
No — 90 minutes is a population average and individual cycles vary by roughly ±20 minutes, and the 15-minute buffer is a rule of thumb. Use it as an anchor to tune by feel; see a doctor for persistent insomnia.
Is Sleep Cycle Calculator free?
Sleep Cycle Calculator is completely free — open the page and use every feature with no hidden charges.
Do I need to download or install Sleep Cycle Calculator?
No download or installation is needed. It is an online tool that runs in the browser on your phone, tablet and computer.
Do I need an account to use Sleep Cycle Calculator?
No. Use the tool right away — no account or sign-in required.
Does Sleep Cycle Calculator work on mobile?
Yes. The page is fully responsive and works on phones, tablets and desktop browsers.