Sleep calculators

Free calculators for bedtimes, wake-up times, naps, sleep debt, caffeine, jet lag and more. Each one explains its method and limits.

Alcohol and sleep

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Alcohol and Sleep Calculator: When to Have Your Last Drink Before Bed

Enter your bedtime and drinks to see the latest time for your last one, so most of the alcohol is processed before you sleep. Not a driving or sobriety tool.

Body clock and light

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Circadian Rhythm Calculator: Map Your Body Clock and Light Timing

Estimate when your melatonin rises, when your body temperature bottoms out, and when light shifts your body clock earlier or later, from your free-day sleep.

Caffeine and sleep

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Caffeine Calculator: How Much Caffeine Is Left at Bedtime

Add your coffees, teas or energy drinks and your bedtime to estimate how much caffeine is still in your body when you lie down, and when it fades.

Chronotype

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Chronotype Calculator: Your Mid-Sleep Point and Social Jet Lag

Turn your real workday and free-day sleep times into a chronotype number (corrected mid-sleep) and your social jet lag, using the method sleep researchers use.

Falling asleep and sleep efficiency

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Sleep Efficiency Calculator: What Percentage of Your Time in Bed You Sleep

Work out your sleep efficiency from one night or a week of sleep diary averages, see whether it is in the normal range, and learn how CBT-I uses the number.

Jet lag

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Jet Lag Calculator: Your Personal Sleep and Light Plan

Enter the time difference and your usual sleep times for a day-by-day trip plan: when to seek light, when to avoid it, and how long adapting may take.

Naps

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Nap Calculator: When to Nap and When to Set Your Alarm

Enter your wake-up time, bedtime and when you can lie down, pick a nap type, and get an alarm time that includes dozing off and leaves room for tonight's sleep.

Shift work

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Night Shift Sleep Calculator: When to Sleep Before and After Your Shift

Enter your night shift times and commute to get a daytime sleep window, an optional pre-work nap, a caffeine cut-off, and a plan for night one and days off.

Sleep cycles and timing

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Sleep Calculator: Bedtime and Wake-Up Times Based on Sleep Cycles

Find a bedtime for your alarm, or a wake-up time for your bedtime, based on sleep cycles and the time you take to fall asleep. Free, with the method explained.

Sleep debt

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Sleep Debt Calculator: How Much Sleep You Owe and How to Repay It

Add up the sleep you missed this week, see your net sleep debt in hours, and get a gentle catch-up plan with a bedtime that fits your usual wake-up time.

Sleep deprivation

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Sleep Deprivation Calculator: How Impaired Are You After Hours Awake?

Count your hours awake and see how lab studies compare that much wakefulness with alcohol, plus crash odds after a short night. If you feel drowsy, don't drive.

Sleep need

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How Much Sleep Do I Need? Sleep Need Calculator by Age

Find the recommended hours of sleep for your age, a personal starting target based on how you sleep and feel now, and the bedtime that fits your alarm.

Sleep schedule

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Sleep Schedule Calculator: A Day-by-Day Plan to Shift Your Bedtime

Enter your wake-up time now and the one you want. Get the number of days it takes and a daily table of wake-up, light, dim-light and bedtime targets.