Sleep Debt Calculator
Enter a week or two of sleep, as hours or as bed and wake times, to see how far you are behind the CDC’s recommended hours for your age: the sleep debt, your average, your shortest night and a simple catch-up illustration.
How to Use
- Choose Hours slept to type each night’s sleep (6.5, 6h30 or 6:30), or Bed & wake times to type pairs such as 23:30-6:45.
- Put one night per line, up to 31 nights, and pick the weekday of the first night so the chart is labelled.
- Choose the age group for the CDC recommendation, or type your own target in hours.
- Set how many nights to spread a catch-up over (7 by default).
- Read the sleep debt, average, shortest night and the catch-up line, and see each night against the target on the chart. To plan a single night, use the Sleep Calculator.
Worked Example
A busy work week. An adult (CDC: 7 or more hours, so a 7-hour target) sleeps 6, 5.5, 6, 6.5 and 5 hours on weeknights, then 8 and 8.5 at the weekend. Total: 45.5 hours. Recommended: 7 × 7 = 49 hours. Sleep debt = 49 − 45.5 = 3 hours 30 minutes. The average is 45.5 ÷ 7 = 6 hours 30 minutes, the shortest night is Friday’s 5 hours, and spreading the debt over 7 nights means 210 ÷ 7 = 30 extra minutes a night.
From bed and wake times. 23:45–6:30 is 6 hours 45 minutes (count to midnight, then on to 6:30). A week of 23:45–6:30, 0:15–6:30, 23:30–6:30, 1:00–6:30, 0:30–6:30, 1:30–9:30 and 23:30–7:30 adds up to 47 hours 30 minutes in bed, 1 hour 30 minutes short of 49: about 13 extra minutes a night for a week.
The common mistake: using the adult figure for a teenager. A 15-year-old sleeping 7 hours every night looks fine against an adult’s 7 hours, with no debt at all. Against the CDC’s 8 hours for ages 13–17, the same week is 7 hours short (56 − 49). Pick the right age group.
Show Work
Formulas
Recommended Hours and Sleep Diaries
The target hours come from the CDC’s “About Sleep” page, which summarises three consensus statements: the National Sleep Foundation’s recommendations (Hirshkowitz et al., 2015), the American Academy of Sleep Medicine’s statement for children and teens (Paruthi et al., 2016) and the joint AASM and Sleep Research Society statement for adults (Watson et al., 2015), which set “7 or more hours” for adults aged 18–60. For babies and children up to 5 the CDC figures include naps.
Writing sleep down night by night is an old clinical habit. The CDC notes that a healthcare provider may ask you to keep a sleep diary of when you go to bed, wake in the night, get up, nap, exercise, and drink alcohol or caffeine, to see what is going on. The list of nights you type here is the sleep part of such a diary.
About This Tool
This calculator adds up one to 31 nights of sleep, entered as hours or as bed and wake times, and compares the total with the CDC’s recommended hours for the age group you choose (the bottom of the range) or with your own target. It nets longer nights against shorter ones, shows the average and the shortest night, draws each night against the target, and spreads any debt evenly over the number of nights you choose as a simple illustration, not a recovery plan.
Everything runs in your browser; nothing you enter is sent anywhere. If you regularly sleep less than you need, or feel sleepy during the day despite enough time in bed, the CDC suggests talking to your healthcare provider.
For general information only — not medical advice. Talk to a doctor or other qualified professional about your own health.
Related tools: Sleep Calculator, Intermittent Fasting Planner, and Heart Disease Risk Calculator.
Frequently Asked Questions
What is sleep debt?
The gap between the sleep you need and the sleep you got, added up over several nights. An adult whose target is 7 hours needs 49 hours over a week; sleeping 6, 5.5, 6, 6.5, 5, 8 and 8.5 hours adds up to 45.5, so the debt is 3 hours 30 minutes. This calculator nets longer nights against shorter ones.
How much sleep do I need?
The CDC recommends 7 or more hours for adults aged 18–60, 7–9 hours at 61–64 and 7–8 hours from 65. Teens aged 13–17 need 8–10 hours and children aged 6–12 need 9–12. This calculator uses the bottom of each range as the target, or your own figure if you enter one.
Can I catch up at the weekend?
Long nights count here: in the week above, Saturday’s 8 hours and Sunday’s 8.5 hours take 2 hours 30 minutes off the shortfall, but 3 hours 30 minutes remain. How far extra sleep makes up for lost sleep is not something a calculator can measure. The CDC’s first tip for better sleep is going to bed and getting up at the same time every day.
Should I enter time in bed or time asleep?
Time asleep, if you know it. Bed and wake times count the whole time in bed: 23:30 to 6:30 is 7 hours, but if you take 20 minutes to fall asleep you slept 6 hours 40 minutes, which is 20 minutes short of a 7-hour target. Many sleep trackers report time asleep directly.
How is the catch-up figure worked out?
It divides the debt evenly over the nights you choose: 3 hours 30 minutes over 7 nights is 30 extra minutes a night, or 15 minutes a night over 14 nights. It is a simple illustration of the arithmetic, not a measured recovery rate or a prescription.
How do I use the Sleep Debt Calculator?
Simply type your numbers and read the result, which refreshes the instant you change something. There is nothing to submit and nothing to wait for.
Is it free? Does it work without internet?
Yes to both. It is free with no sign-up, and once the page has loaded it keeps working even with no internet.
Where does my data go?
Nowhere — every calculation runs on your own device. Nothing you enter is uploaded, logged, or stored.
Common Use Cases
A busy work week
Nights of 6, 5.5, 6, 6.5 and 5 hours, then 8 and 8.5 at the weekend, average 6 hours 30 minutes: 3 hours 30 minutes short of an adult’s 7-hour target.
A teenager in term time
A 15-year-old sleeping 7, 6.5, 7, 6, 6.5, 9.5 and 10 hours averages 7 hours 30 minutes, 3 hours 30 minutes below the CDC’s 8 hours a night for teens.
From a sleep diary
Bed and wake times from 23:45–6:30 through to 23:30–7:30 over a week come to 47 hours 30 minutes in bed, 1 hour 30 minutes short of 49; about 13 extra minutes a night would cover it in a week.
Two weeks at once
Fourteen nights totalling 93 hours against 98 recommended leave a 5-hour debt and an average of 6 hours 39 minutes; spread over 14 nights that is 22 minutes a night.
Your own target
Someone who feels best on 8 hours and slept 7.5, 7, 7.5, 7, 6.5, 9 and 8.5 is 3 hours behind (53 of 56 hours).
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