Sleep Calculator — Bedtime & Wake Up Time

Free sleep calculator. Find the best time to sleep and wake up based on 90-minute sleep cycles. Sleep planner for optimal rest and energy levels.

Sleep Calculator

Includes ~15 minutes to fall asleep. Based on 90-minute sleep cycles.

How to Use

Choose your mode — "I want to wake up at" or "I want to go to bed at".

Enter the time. The calculator automatically adds 15 minutes to fall asleep.

See optimal times based on 3-6 complete sleep cycles. Green = recommended, amber = okay, red = minimum.

What is a Sleep Calculator?

A sleep calculator helps you find the ideal time to go to sleep or wake up based on your natural sleep cycles. Each cycle lasts about 90 minutes. Waking up at the end of a cycle — rather than in the middle of one — helps you feel refreshed and energized. The calculator accounts for the average time it takes to fall asleep (about 15 minutes) and suggests times for 3 to 6 complete cycles.

Frequently Asked Questions

What is a sleep cycle?
A sleep cycle lasts approximately 90 minutes and includes light sleep, deep sleep, and REM sleep stages. Most adults need 5-6 complete cycles (7.5-9 hours) per night.
Why does waking between cycles matter?
Waking up during deep sleep causes grogginess. Waking at the end of a cycle — during light sleep — helps you feel refreshed and alert, even with less total sleep.
How long does it take to fall asleep?
The average person takes about 15 minutes to fall asleep. The calculator adds this time automatically when calculating bedtimes.
How many hours of sleep do I need?
Adults typically need 7-9 hours (5-6 cycles). Teenagers need 8-10 hours. Children need 9-12 hours depending on age.
What if I want to wake up at a specific time?
Select "I want to wake up at" and enter your desired wake time. The calculator will show you the best times to go to bed.

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