How much sleep do you owe yourself?
Drag in roughly how long you slept each night this past week. We'll add up your sleep debt and show you how to pay it back.
Hours you actually slept
What is sleep debt?
Sleep debt is the gap between the sleep your body needs and the sleep it gets, added up night after night. Need eight hours, get six, and you are two hours down — five nights of that is a full night of sleep missing, without any single night feeling like a disaster. The longer explanation is here.
How this calculator works
Pick the sleep you need each night, then drag in roughly what you actually slept for each of the last seven nights. For every night we subtract what you slept from what you need. Short nights add to the total; longer ones pay some of it back. The bar chart shows each night against your need line, and the figures underneath show how many nights of a slightly earlier bedtime would clear what is left.
It runs entirely in your browser. Nothing you type is sent anywhere or stored — reload the page and it is gone. There is no sign-up, and there never will be.
Two things worth knowing about the number
Time in bed is not time asleep. Most people overestimate by half an hour or more, so if you are entering the time between lights-out and the alarm, your real debt is probably larger than this says.
Seven days is a convention, not a measurement. There is no organ keeping a balance — the total is produced by subtraction, and the window is a choice. It is a useful way to see a pattern, not a reading off a gauge. We wrote about where that metaphor breaks in is sleep debt real?
Common questions
How do you calculate sleep debt? Subtract the hours you slept from the hours you need, for each night, and add the differences across a window — usually seven or fourteen nights. Longer nights offset short ones. That is exactly what this page does with the seven figures you give it.
How much sleep debt do I have? There is no way to know without counting, and counting is the point of this page — because your sense of how rested you are stops tracking the deficit quite early. In the best-known experiment on this, people held to six hours a night for two weeks kept getting measurably worse while their own ratings of their sleepiness levelled off.
How much sleep do I actually need? Most adults land between seven and nine hours. If you wake without an alarm after a few consistent nights and get through the afternoon without caffeine propping you up, you are close. If you sleep far longer whenever you can, you are probably carrying a debt.
Can I clear sleep debt by sleeping in at the weekend? Not really, and it may be worse than it sounds — a 2019 study found a catch-up weekend failed to prevent the metabolic effects of short sleep, and left insulin sensitivity worse than in people who never caught up. What does work is here.
If the number never comes down
A debt that will not clear despite enough time in bed is usually not a debt. Waking unrefreshed, daytime sleepiness despite long nights, heavy snoring or being told you stop breathing in your sleep can point to conditions such as sleep apnoea or insomnia — common, treatable, and not fixed by an earlier bedtime. This is a calculator, not a diagnosis. See a doctor.