TranslateSleep Cycle Calculator
Find your ideal bedtime or wake-up time based on 90-minute sleep cycles, track your sleep score, streaks, and badges.
Recommended: 7-9 hours/night
5:15 AM
4 cycles · 6.0h sleep
Estimated Sleep Stages
6:45 AM
5 cycles · 7.5h sleep
Estimated Sleep Stages
8:15 AM
6 cycles · 9.0h sleep
Estimated Sleep Stages
How to Use This Sleep Calculator
Workflow
- Use the Sleep Calculator to find optimal bedtimes or wake times based on 90-minute sleep cycles.
- Check the Nap Calculator to see exactly when you should wake up from a nap to avoid grogginess.
- Use the Caffeine Cutoff tab to calculate when to stop drinking coffee so it doesn't disrupt your sleep.
- Log your sleep daily in the Sleep Log to track your sleep score, streaks, and pay off sleep debt.
Understanding the Metrics
- Sleep Cycles: Waking up at the end of a 90-minute cycle helps you feel refreshed.
- Sleep Score: Calculated based on duration, cycle alignment, bedtime consistency, and optimal timing.
- Sleep Debt: The gap between the sleep you got and what you needed over the last 7 days.
- Data Privacy: All your sleep logs are saved locally in your browser. Nothing is uploaded to a server.
About This Tool
The Sleep Cycle Calculator is a free online tool that helps you wake up feeling refreshed instead of groggy. Have you ever slept for 8 or 9 hours but still woken up feeling like you got hit by a truck?
That happens because your alarm went off while you were in the middle of a deep sleep cycle. This tool uses the science of 90-minute sleep cycles to calculate the exact time you should go to bed or wake up.
It also includes a nap calculator, a caffeine cutoff timer, and a sleep score tracker with streaks and badges to help you build a healthier bedtime routine. Everything runs instantly in your browser.
How to Use
- 1Choose if you want to find out when to "Go to Sleep" or when to "Wake Up".
- 2If you know when you need to wake up, enter that time to see the best times to fall asleep.
- 3If you are going to bed right now, enter your current time to see the best times to set your alarm.
- 4Use the Nap Calculator to find the perfect length for a quick power nap without waking up tired.
- 5Check the Caffeine Calculator to see exactly when you should have your last coffee of the day.
- 6Track your sleep score and try to earn badges by keeping a consistent streak!
Frequently Asked Questions
Human sleep happens in cycles of roughly 90 minutes, moving from light sleep to deep sleep and back. If your alarm wakes you up in the middle of a deep sleep cycle, you will feel groggy and exhausted. Waking up at the end of a cycle makes you feel alert and refreshed.
Caffeine has a half-life of about 5-6 hours, meaning it stays in your system long after you drink it. The calculator looks at your target bedtime and tells you the exact cutoff time to stop drinking coffee so it doesn't ruin your deep sleep.
A 20-minute nap is perfect for a quick energy boost without feeling groggy. If you are highly sleep-deprived, a 90-minute nap allows you to complete one full sleep cycle. The tool will help you set a timer for both.
The tool tracks your sleep score locally. By consistently going to bed and waking up at the times recommended by the calculator, you improve your sleep score, build streaks, and unlock fun digital badges to keep you motivated.
Your sleep score and streaks are saved locally in your browser, but they are never uploaded to a server. Your personal sleep habits and bedtimes remain completely private.
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