What is the best time to wake up?

The best time to wake up is aligned with your sleep cycles, ideally after 4-6 full cycles (each ~90 minutes).

How many hours of sleep do adults need?

Adults generally need 7-9 hours of sleep per night for optimal health.

No, it provides guidelines for sleep cycles. For sleep disorders, consult a healthcare professional.

Yes, CalHub's Sleep Calculator is completely free to use.

No, all calculations are done locally in your browser and no data is stored.

Find optimal bedtimes or wake-up times based on 90-minute sleep cycles for better rest.

I want to wake up at:

OR I want to go to bed at:

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Sleep occurs in cycles of ~90 minutes. Waking up at the end of a cycle helps you feel refreshed, while waking up mid-cycle can cause grogginess.

Enter your desired wake-up time to get optimal bedtimes, or enter bedtime to get wake-up times.
Click “Calculate Optimal Times”.
Follow the suggested times for better sleep quality.

Aim for 4-6 full sleep cycles per night (6-9 hours of sleep).

You may feel groggy and tired. This is why timing sleep cycles is helpful.

Yes, it is free and can be used daily to plan your sleep schedule.

No, consult a healthcare professional for sleep disorders.

No, all calculations are done locally in your browser.