# CheckWhenDone

> Put the habit on paper. Print a tracker, hang it where you can't miss it,
> and check a box every time you follow through. The paper keeps score.
> Free, no account, and prints on one A4 page.

There is no magic number for forming a habit. Choose the behavior, print
your tracker, and keep checking it off.

## What you can do here

- Build a habit check sheet with a live A4 preview at [/print](https://checkwhendone.com/print)
- Pick active weekdays so every box gets a real date, or keep a plain numbered grid
- Add up to 6 numbered daily rules below the boxes
- Add up to 3 links that print as QR codes on the sheet
- Scan the "Print more" QR code every sheet carries in its bottom right corner to reprint it
- Share or reprint a sheet: the whole configuration lives in the URL

## Why repetition?

### How long does it take to form a habit?

There isn't a universal number.

In one real-world study, people repeated a new behavior daily in a consistent
context. Among participants whose habit development could be modeled reliably,
the median estimated time to reach 95% of maximum automaticity was 66 days. The
middle half of estimates was roughly 39 to 102 days, and modeled estimates
ranged from 18 to 254 days.

The takeaway isn't "66 days." Habit formation is gradual and highly individual.
In the same study, missing one opportunity did not appear to materially disrupt
the process.

CheckWhenDone does not promise that a habit will form after a certain number of
checks. The checks help you repeat the behavior and make your progress visible.

Source: Lally et al. (2010), *How are habits formed: Modelling habit formation
in the real world*, European Journal of Social Psychology.
[DOI: 10.1002/ejsp.674](https://doi.org/10.1002/ejsp.674)

## Pages

- [Sheet configurator](https://checkwhendone.com/print): build and print a sheet
- [About](https://checkwhendone.com/about): what this site is and who runs it
- [Contact](https://checkwhendone.com/contact): how to reach the maintainer
- [Privacy](https://checkwhendone.com/privacy): what data is and is not collected

For machine-readable guidance, see [llms.txt](https://checkwhendone.com/llms.txt) and the
[sitemap](https://checkwhendone.com/sitemap.xml).