Seven nights, one subtraction
What is usually called a sleep debt calculator, done as the subtraction it is. Put in what you actually slept and the page takes your target off it. That is the whole calculation. It says how far the week ran under or over a number you chose yourself, and it has no opinion about whether the number was right.
| Night | Slept | Against target |
|---|---|---|
| — | ||
| — | ||
| — | ||
| — | ||
| — | ||
| — | ||
| — | ||
| The week | 0m of 0m | — |
no nights filled in yet. Blank nights are left out of both totals, so a half-filled week is compared against a half week and not against seven.
The seven numbers and the target are saved in this browser, on this device. They are not sent anywhere, there is no account they could be attached to, and nobody operating this site can see them. Clearing the site's data in your browser removes them, and so does the button above.
The key is listed by name on the cookies and storage page with everything else this site keeps.
Why it is not called a debt here
Sleep debt is the name people search for, and the figure in the last row is the one a sleep debt calculator prints: the hours a week fell short of a target, added up. The word is borrowed from money, and the borrowing stops at the arithmetic. A debt has a lender, a rate and a way of paying it back, and this page has none of the three. It can subtract, so the figure is called what it is, the difference.
What a running total is and is not
It is the difference between two numbers you supplied. It is not a debt in any sense that can be repaid at a fixed rate, this site does not claim that sleeping longer at the weekend settles anything, and the arithmetic would be identical if the subject were rainfall.
The target is yours because nobody here is in a position to set one for you. If you have no figure in mind, the site's default is seven and a half hours, which is five cycles of the length the rest of the site assumes, and it is a default rather than a recommendation.
Where the nights come from
If you are choosing a bedtime rather than recording one, the arithmetic runs the other way on the wake-time pages, which count backwards from an alarm.