Online Calendar

A month-view calendar for any year, past or future, with ISO week numbers down the side, an automatic leap-year flag, and the current quarter shown — details a plain paper calendar or a phone's calendar app usually leaves out but that come up regularly in business and project planning.

ISO week numbers

Week numbering here follows ISO 8601, which defines week 1 of the year as the week containing the year's first Thursday, and the week itself as running Monday to Sunday. That is why the calendar starts each row on Monday rather than Sunday — matching the convention used across most of Europe, and in business software like Outlook and Excel when it reports a week number.

Leap years

A year is a leap year if it divides evenly by 4 — except century years, which only qualify if they divide evenly by 400 as well. That extra rule is why 2000 was a leap year but 1900 was not, and it is applied automatically whenever you jump to February in a given year.

Printing a clean sheet

The print view strips out navigation, header and every other piece of site furniture, leaving just the month grid — useful for a wall calendar, a planning sheet, or handing a printed month to someone without a screen.