See how much sleep you’ve missed. This free sleep debt calculator compares your nightly target with actual hours slept over the week, showing total debt, average sleep and shortfall.
This is a simple estimate of sleep debt for general wellbeing. Most adults need about 7–9 hours a night. Ongoing tiredness, trouble sleeping or daytime sleepiness can have many causes — if poor sleep is affecting your life, it’s worth speaking with a doctor.
Your sleep
hours
Hours slept each night (last 7)
Set your nightly target, then enter how many hours you actually slept on each of the last seven nights. Leave a night blank if you’d rather not include it.
Sleep debt this week
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Enter your target and nights
Nights counted
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Average / night
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Avg shortfall / night
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Total sleep
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Sleep debt is the gap between the sleep you need and the sleep you get, added up over time. You can’t fully “bank” or repay it in one night, but a few nights of consistent, slightly longer sleep and a steady schedule help you recover.
Use this free sleep debt calculator to see how much sleep you’ve missed. Enter your nightly target and the hours you slept over the last week to find your accumulated sleep debt.
What this sleep debt calculator does
A sleep debt calculator compares the sleep you aim for with the sleep you actually get, adding up the shortfall across the week into a single sleep-debt figure.
How sleep debt is calculated
sleep debt = (target per night × nights) − total slept
average = total slept ÷ nights
So aiming for 8 hours but sleeping 6.5 for seven nights builds a debt of 10.5 hours in a week.
How much sleep do adults need?
Age group
Recommended sleep
Teenagers (14–17)
8–10 hours
Adults (18–64)
7–9 hours
Older adults (65+)
7–8 hours
Can you catch up on sleep?
Partly. You can’t repay a big sleep debt in one long lie-in, and over-sleeping at weekends can disrupt your rhythm. The most effective recovery is consistent, sufficient sleep with a steady schedule over several nights.
How to use the sleep debt calculator
Set your nightly sleep target.
Enter the hours slept for each of the last seven nights.
Read your weekly debt, average and shortfall.
Sleep Debt FAQ
What is sleep debt?
It's the running total of sleep you've missed — the difference between the sleep you need and the sleep you get, added up over time.
How do I calculate my sleep debt?
Multiply your nightly target by the number of nights, then subtract your total sleep. Aiming for 8 hours but getting 6.5 for a week is a 10.5-hour debt.
Can you catch up on lost sleep?
Partly. You can recover some with a few nights of consistent, slightly longer sleep, but a single long lie-in won't fully repay a large debt.
How much sleep do I need?
Most adults need 7–9 hours a night, teenagers a little more. Individual needs vary, so use what leaves you rested.
Is sleep debt bad for you?
Ongoing sleep debt is linked to poorer focus, mood and health. Consistent, sufficient sleep is the best fix; persistent problems are worth discussing with a doctor.
Is the sleep debt calculator free?
Yes, this sleep debt calculator is completely free, needs no sign-up, and gives instant results in your browser.
