Sleep Calculator

Free sleep calculator based on 90-minute sleep cycles. Enter your bedtime to see optimal wake times, or enter your wake time to see when to go to bed. Accounts for 15 minutes to fall asleep. Includes age-based sleep recommendations and sleep quality tips.

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How to Use Sleep Calculator

1Choose mode: 'When to wake up' or 'When to go to bed'.
2Enter your bedtime or desired wake time.
3View recommended times based on sleep cycles.
4Select the option that gives you enough cycles.

Frequently Asked Questions

It calculates based on 90-minute sleep cycles. Waking between cycles (rather than mid-cycle) helps you feel more refreshed.

Adults need 7-9 hours (4-6 sleep cycles). Teens need 8-10 hours. Children need 9-12 hours depending on age.

You may be waking mid-cycle. Try adjusting your wake time by 15-30 minutes to align with a cycle boundary.

The Sleep Calculator is a free online tool that lets you find optimal bedtime or wake time based on 90-minute sleep cycles. It is part of NexTool's collection of free tools designed to help you work faster and more efficiently.

Yes, the Sleep Calculator is 100% free to use with no limitations. There is no registration required, no daily usage caps, and no hidden fees. You can use it as many times as you need.

Yes, the Sleep Calculator is fully responsive and works on any device with a modern web browser, including smartphones, tablets, laptops, and desktops. No app installation is needed.

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About Sleep Calculator

NexTool's Sleep Calculator is completely free to use with no sign-up required. Your data is processed directly in your browser and never sent to our servers, ensuring complete privacy and instant results.

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Sleep Calculator

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Wake-up time

Assumes ~15 min to fall asleep. Each cycle = 90 min.

9:45 PM

6 cycles · 9.0 hrs

Optimal

11:15 PM

5 cycles · 7.5 hrs

Optimal

12:45 AM

4 cycles · 6.0 hrs

Good

2:15 AM

3 cycles · 4.5 hrs

Minimum

🌙 Sleep Cycle Stages

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