Months With Same Calendar

A month grid match is narrower than a full-year match. Two months print the same calendar page when they have the same length and the same starting weekday. January 31 starting on Thursday matches any other 31-day month that also starts on Thursday, even in a different year. February is the exception: a 28-day February never matches a 29-day February, because the extra day changes both the grid and the weekday of March 1.

Length plus start weekday

Month length is 28, 29, 30, or 31 days. Start weekday is the weekday of the 1st. Those two numbers fix every cell in a seven-column grid. A 30-day month that starts on Saturday ends on Sunday; a 31-day month that starts on Saturday ends on Monday. Mixing those lengths produces a different last row even when the 1st is the same weekday.

This is not the same test as years with the same calendar. A year match requires every month of that year to line up. A month match can pair March of one year with August of another. People who reprint a single month page—desk pads, classroom number lines, billing inserts—need the month test, not the year test.

February only matches February of the same length

Common-year February has 28 days. Leap-year February has 29. A 28-day February that starts on Monday is a different grid from a 29-day February that starts on Monday: the 29th occupies an extra cell, and the following March 1 shifts. The tool therefore never lists a leap February as a match for a common February, even if both start on the same weekday.

Thirty-day months (April, June, September, November) form one pool. Thirty-one-day months (January, March, May, July, August, October, December) form another. Crossing those pools is never a grid match. April starting on Wednesday is not a match for May starting on Wednesday.

How to use the month matcher

Pick a month and year, then calculate. The list shows other months that share length and starting weekday. Nearby years are handy for leftover desk-pad stock. Distant years help template libraries that store one PDF per (length, start-weekday) pair rather than 12 × N year files.

After you reuse a month page, still check holidays for that civil month on 2026 holidays if the reprint is for 2026. Observed federal dates are not part of the grid match. A reused March grid can still have a different observed Memorial Day weekday in May, which is a different month entirely.

Worked examples

A copy shop has leftover April grids from a year when April started on Tuesday and had 30 days. They enter that April, then scan the match list for a future April, June, September, or November with the same start weekday before printing new stock. If next April is not listed, they do not force the old file by covering the year in the header.

A payroll clerk wants a November timesheet that looks like last March because both months started on the same weekday and both have 31 days. They confirm the pair here, then still mark pay dates separately with pay period calendar because pay anchors are not implied by month shape.

Week start does not change the match

Sunday-start and Monday-start calendars rearrange columns but do not change which date is the 1st or how many days the month has. Two months that match under this tool still match after you switch week start; only the blank cells at the beginning of the first week move from the left of Sunday to the left of Monday.

ISO week numbers printed in the margin can still differ between matching months, because ISO weeks belong to a Monday-based year count. If you need week numbers on the page, generate a labeled year on week number calendar rather than assuming a reused month carries the same ISO week labels.

False friends people mix up

Same starting weekday with different lengths is the most common false friend. January 1 on Friday in a 31-day month is not August in a 31-day month unless August 1 is also Friday. People remember “it started on Friday” and forget to check length. The tool requires both.

Same length with different start weekdays is the other trap. Two 30-day months that start on Monday versus Tuesday print different weekends on the 1st–2nd and different last-row leftovers. Reusing the PDF would put Saturday boxes on the wrong dates.

Print inventory and classroom sets

Schools that photocopy a blank month and write the year by hand can keep four folders: 28, 29, 30, and 31, each subdivided by start weekday. This matcher tells which folder to pull for a given civil month. It does not count instructional days or snow days; those belong on school-specific tools.

Retailers reprinting a promotional month insert should still replace seasonal art and legal holiday callouts. Grid reuse is a typesetting shortcut, not a marketing reuse of last year’s campaign dates.

Template libraries and file names

Name reusable month PDFs by length and start weekday, for example 31-Thursday, rather than by a single month name. August and January can share a file when both are 31-Thursday. A 29-day February that starts on Monday never shares a folder with a 28-day February that starts on Monday. That naming stores the matcher’s two-factor test in the filename so a designer does not open the wrong February.

When a reprint is for 2026, still replace the year in the header even if the grid is a match from a decade ago. Readers notice a stale year faster than they notice a correct weekday column. Keep holiday stamps out of the master PDF so each reuse does not inherit last year’s observances.