A printable calendar fails most often at the printer, not in the grid. The last weekday column sits on the right. If the job is scaled to “fit” or the paper size is wrong, that column is the first thing to disappear.
Set the paper control on the page to the sheet in the tray. Letter is 8.5 by 11 inches. A4 is 210 by 297 millimeters. Then open Print / Save as PDF. In the dialog, choose the same size. Turn off “Fit to printable area” or “Fit to page” if you have that option. Prefer 100 percent / actual size.
Match orientation. A landscape month printed as portrait will crop the right side. The site asks the browser for Letter or A4 in the orientation you selected, but some browsers still default to the last job’s settings. Look at the preview in the dialog. You should see a full Saturday column (or a full Sunday column on a Monday-start sheet).
Most home printers cannot print to the physical edge. That is normal. The template already keeps an inner margin. Do not add a second large margin in the dialog if the preview already shows space around the grid. Browser headers and footers (the URL and date) steal space. Turn those off.
If a driver still clips, try “Save as PDF,” then print the PDF from a reader with actual size. That two-step path avoids a second fit-to-page. For a yearly 12-up sheet, check that the smallest day numbers are not sitting in the unprintable strip; switch to high contrast if they look faint rather than enlarging past 100 percent.
The month engine uses six rows so a month that needs a sixth week does not lose the last dates. Clipping is almost always a print-scale problem, not a missing week in the template.
A short checklist
Paper size matches. Orientation matches. Scale is 100 percent. Headers and footers are off. The dialog preview shows seven weekday headers and the last column. Then print.