The Sleep Calculator collection helps you work with your body's natural rest patterns. Plan bedtime or wake time with the 90 Minute Sleep Cycle Calculator, quantify missed rest with the Sleep Debt Calculator, measure daytime drowsiness with the Epworth Sleepiness Scale, and screen for apnea risk with the STOP-BANG Sleep Apnea Calculator.
Browse the Popular list to see which tools other users turn to most, or open the Trending tab to discover what's resonating right now. All calculators are free, need no login, and work on any device.
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Sleep Duration CalculatorCalculate how many hours and minutes you slept between bedtime and wake time. Handles sleep that crosses midnight with simple mod-24 math.
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Hours of Sleep CalculatorFind out how much sleep you'll get tonight. Enter your bedtime and wake time to calculate total sleep hours, minutes, and 90-minute sleep cycles.
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Caffeine Half-Life CalculatorEstimate how much caffeine is still in your body using the half-life decay formula. See remaining mg at bedtime from your coffee, tea or energy drink.
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Bedtime CalculatorFind the best time to go to bed for your wake-up time. Calculates bedtimes based on 90-minute sleep cycles plus time to fall asleep.
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Jet Lag Recovery CalculatorEstimate how many days you need to recover from jet lag based on time zones crossed and travel direction (eastward vs westward).
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Alarm Time CalculatorFind what time to set your alarm. Add bedtime, time to fall asleep, and desired sleep hours to get your exact 24-hour wake-up time.
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Caffeine Cutoff Time CalculatorFind your caffeine cutoff time — the latest hour to drink coffee before bed. Enter your bedtime and a cutoff window (default 6 hours) for better sleep.
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Sleep Quality Score CalculatorCalculate your Sleep Quality Score (0-100) from time in bed, time asleep, and awakenings using a weighted efficiency, duration, and continuity formula.
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Power Nap CalculatorFind the best wake-up time for a 20-minute power nap or 90-minute full sleep cycle, including the time it takes you to fall asleep.
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Deep Sleep CalculatorEstimate how many minutes of deep sleep you get each night from your total sleep time and deep sleep percentage. Free, instant deep sleep calculator.
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Baby Wake Window CalculatorFind your baby's next nap or bedtime. Enter age and last wake-up time to get an age-appropriate wake window and recommended sleep time.
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Total Sleep Time CalculatorCalculate how many hours you slept between your bedtime and wake time. Handles overnight sleep and subtracts minutes spent awake during the night.
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Sleep Efficiency CalculatorCalculate your sleep efficiency as a percentage from total sleep time and time in bed. See how much of your night in bed was actually spent asleep.
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Sleep Cycles CalculatorCalculate how many sleep cycles you completed from your total sleep time. Each cycle is about 90 minutes — enter hours and minutes to see your count.
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Sleep Cycle CalculatorFree sleep cycle calculator. Find the best bedtime or wake-up time based on 90-minute sleep cycles plus the time it takes you to fall asleep.
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Melatonin Onset Timing CalculatorFind out exactly when to take melatonin before bed. Enter your target sleep time and onset lag (30–60 min) to get the ideal dose time.
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Sleep Need CalculatorEstimate how many hours of sleep you need tonight based on your age, recent sleep debt, and activity level. Free, instant sleep need calculator.
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Naps Needed CalculatorEstimate how many naps per day are needed from total daytime sleep hours and average nap length. Free, instant nap schedule calculator for babies and adults.
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Average Sleep Per Night CalculatorCalculate your average sleep per night from a week of nightly hours. Enter each night's sleep to find your weekly mean and total sleep instantly.
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Ideal Bedtime by Age CalculatorFind your child's ideal bedtime by age. Enter wake-up time and age to get a recommended bedtime based on healthy sleep guidelines for kids.
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Multiple Wake-Up Time Options CalculatorEnter your bedtime to find the best wake-up times based on 90-minute sleep cycles — 4.5, 6, 7.5 and 9 hours of sleep so you wake refreshed.
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Insomnia Severity Index (ISI) CalculatorCalculate your Insomnia Severity Index (ISI) score by summing 7 items (0–4 each, range 0–28) and get the standard severity interpretation.
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Pittsburgh Sleep Quality Index (PSQI) CalculatorCalculate your global Pittsburgh Sleep Quality Index (PSQI) by summing 7 component scores (0-3 each) for a 0-21 total. Scores above 5 suggest poor sleep.
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Sleep Apnea AHI CalculatorCalculate your Apnea-Hypopnea Index (AHI) from apneas, hypopneas, and sleep time, and see the sleep apnea severity category (normal, mild, moderate, severe).
Frequently asked questions
What can I figure out with these sleep calculators?
You can find the best bedtime or wake time aligned to 90-minute sleep cycles, estimate accumulated sleep debt over a week, score your daytime sleepiness with the Epworth scale, assess obstructive sleep apnea risk using the STOP-BANG questionnaire, and calculate melatonin dosage timing with the Melatonin Dosage Calculator.
Are the sleep calculators free to use?
Completely free — no account required, no app to download, no paywall. Every tool opens instantly on any smartphone, tablet, or desktop browser.
How accurate are the results?
The tools are built on validated clinical instruments and established sleep science, including the standard 90-minute cycle model and the STOP-BANG questionnaire. Results are useful estimates for self-awareness and lifestyle adjustments. These calculators are NOT a substitute for medical advice. If you have concerns about sleep quality, disorders, or medication, consult a qualified healthcare professional.
Do you save or share my answers?
No. Everything runs in your browser — your responses to questionnaires like the Epworth Scale or STOP-BANG are never sent to our servers, stored, or shared with anyone. Close the tab and the data is gone.
Which sleep calculators are most popular?
The Popular list ranks every tool by actual visitor usage, putting the most-used calculators at the top. You can also check Trending for fast-rising tools, Recently Added for new additions, or Last Updated for freshly reviewed calculators.
