Health calculator

Sleep Calculator by Wake Time

Find bedtimes or wake times based on 90-minute sleep cycles.

FormulaBedtime = wake time - sleep cycles x 90 minutes

Formula

Sleep cycle estimate

Bedtime = wake time - sleep cycles x 90 minutes

For 5 cycles before 7:00 AM, bedtime is about 11:30 PM.

FAQ5 common questions for this calculator.

FAQs

Why 90-minute cycles?+

Sleep cycles are often approximated at about 90 minutes, though real sleep varies.

How does the Sleep Calculator calculate the result?+

For the Sleep Calculator, it uses the Sleep cycle estimate: Bedtime = wake time - sleep cycles x 90 minutes. For 5 cycles before 7:00 AM, bedtime is about 11:30 PM.

What information do I need to use the Sleep Calculator?+

Enter the body, activity, serving, or nutrition values requested by the form. Use the same unit system throughout so the Sleep Calculator result is comparable.

How accurate is the Sleep Calculator?+

Sleep Calculator is only as accurate as the body measurements and activity details entered. It applies the Sleep cycle estimate shown on this page, then rounds for readability. Treat the output as screening guidance rather than a diagnosis.

What should I check before using the Sleep Calculator result?+

For the Sleep Calculator, check the body measurements and activity settings, unit choices, and whether the calculator's assumptions fit the person being assessed. Use the result as screening or planning context, not as a diagnosis.

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Health guide

How to use the Sleep Calculator

Find bedtimes or wake times based on 90-minute sleep cycles. The page also explains the sleep cycle estimate and shows a practical example: For 5 cycles before 7:00 AM, bedtime is about 11:30 PM.

  1. 1

    Enter your details

    Enter the values for the sleep calculator scenario you want to check.

  2. 2

    Check the calculation

    Review the result alongside the sleep cycle estimate: Bedtime = wake time - sleep cycles x 90 minutes.

  3. 3

    Compare scenarios

    Change one or more inputs to see how they affect the sleep Calculator result before you use the estimate.