Why start the week on Monday
A Monday start calendar matches how many people plan work. The five weekdays read left to right, and the weekend is a pair of boxes on the right. ISO week numbers also assume a Monday start. If you turn on ISO weeks on a monthly layout, the gutter labels those weeks while the columns still follow the start you chose.
This page defaults to a classic monthly Monday layout. The same start applies to yearly 12-up sheets, weekly planners, and blank grids. Change Week starts back to Sunday if you are printing for a household that grew up with Sunday-first wall calendars.
Check the first column in the preview before you print. January 1 will not always sit under Monday; it sits under whatever weekday it is. The first column is the start of the week, not “the first of the month.”
Letter and A4 both work. A grayscale office preset pairs a Monday start with a notes column and ISO weeks for a cubicle wall. That preset is in the gallery if you want the whole bundle at once.
The Sunday versus Monday guide compares the two habits without telling you that one is official. Neither start is a legal requirement on a homemade print.