FREE HEALTH TOOL
Sleep Calculator
Calculate the ideal bedtime or wake-up time based on 90-minute sleep cycles so you wake up feeling refreshed.
I want to wake up at...
09:46 PM
Go to bed at - 6 sleep cycles - 9 hrs sleep
11:16 PM
Go to bed at - 5 sleep cycles - 7.5 hrs sleep
12:46 AM
Go to bed at - 4 sleep cycles - 6 hrs sleep
How it works
Sleep happens in cycles of about 90 minutes each. Waking up at the end of a cycle - rather than in the middle - leaves you feeling refreshed. These times include 14 minutes to fall asleep. Results are estimates; adjust based on how long it takes you personally.
Why Use Our Sleep Calculator?
Based on Sleep Science
Sleep happens in 90-minute cycles. Waking at the end of a cycle leaves you refreshed instead of groggy.
Two Calculation Modes
Enter your wake-up time to find when to go to sleep, or enter your bedtime to find when to wake up.
Go to Bed Now Mode
Tap the button to instantly calculate wake-up times based on the current time - no input needed.
Three Sleep Duration Options
See results for 6 cycles (9 hrs), 5 cycles (7.5 hrs), and 4 cycles (6 hrs) rated Recommended, Good, or Minimum.
Fall-Asleep Time Included
Adds the average 14 minutes it takes to fall asleep so your actual sleep time is accurately calculated.
No Sign-up Required
Open the page and get your ideal sleep schedule in seconds. No account or personal data needed.
Frequently Asked Questions
How does the sleep calculator work?
It calculates sleep times based on 90-minute sleep cycles. Waking at the end of a cycle means you complete the cycle naturally and feel more alert.
Why 90 minutes per cycle?
The average human sleep cycle lasts approximately 90 minutes and includes light sleep, deep sleep, and REM stages. Multiple research studies support this as the standard cycle length.
What is the 14-minute fall-asleep time?
Most people take an average of 14 minutes to fall asleep after lying down. The calculator adds this to your bedtime so your sleep cycle timing is accurate.
Which option should I choose - Recommended, Good, or Minimum?
Recommended (6 cycles, 9 hours) is ideal for most adults. Good (5 cycles, 7.5 hours) is a solid target. Minimum (4 cycles, 6 hours) should be used occasionally, not routinely.
What is the Going to Bed Now option?
Tapping this button instantly calculates wake-up times based on the current time, so you do not need to enter anything when you are about to sleep.
Is this sleep calculator scientifically accurate?
It is based on widely accepted sleep science. However, individual sleep cycles vary between 80 and 120 minutes. Use the results as a guide and adjust based on how you feel.
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