Habit tracker, A4
Thirty-one day columns on A4, sized to sit in a standard European binder or notebook.
Opens with these settings already loaded. Change anything you like, then download as PDF, PNG or SVG.
A month on one page
Thirty-one columns covers the longest month, and you leave the surplus blank in shorter ones. A month is the right window because a week is too short to show a pattern and a year is too long to look at without flinching. It also ends often enough that a bad month can be abandoned without abandoning the habit itself, which is the failure mode that kills most tracking.
Three to five habits, no more
The common mistake is a tracker with a dozen rows, which becomes a record of failure by the middle of the second week. Keep it to three to five. Prefer things that are unambiguously done or not done, because "ate well" is a judgment you will argue with yourself about at eleven at night while "walked 20 minutes" is not. If a habit needs a number rather than a mark, write the number in the box.
A4 for European binders
A4 is the standard filing size across Europe, so an A4 tracker punches into an ordinary binder and sits with everything else. If you keep a bullet journal instead, print at A5 and tuck it against the current spread. The Letter version is the US equivalent.
Printing it accurately
This only measures correctly if your printer doesn't rescale the page. In the print dialog set Scale: 100%, not "Fit to page" or "Shrink oversized pages". If you're not sure it worked, print the calibration page, measure the ruler on it with a real ruler, and it will tell you exactly what your printer is doing to the page.