Interactive Calendar
Browse months, click on any date to see details, and navigate freely between years. Today's date is highlighted for quick reference.
About the Calendar
The Gregorian calendar, used worldwide for civil purposes, was introduced by Pope Gregory XIII in 1582. It organizes a year into 12 months of varying lengths: January (31 days), February (28 or 29), March (31), April (30), May (31), June (30), July (31), August (31), September (30), October (31), November (30), and December (31). A common year has 365 days, while a leap year has 366.
Leap year rules: A year is a leap year if it is divisible by 4, except for century years, which must be divisible by 400. This means 2000 and 2400 are leap years, but 1900, 2100, and 2300 are not. The extra day is added to February, giving it 29 days instead of 28.
ISO week numbering: Under the ISO 8601 standard, weeks start on Monday and the first week of the year is the one containing the first Thursday of January. Most years have 52 ISO weeks, but years where January 1 falls on a Thursday (or Wednesday in leap years) have 53 weeks. Click any date above to see its ISO week number, day of the year, and quarter.
Frequently Asked Questions
Use the left and right arrow buttons to move one month at a time, or use the month and year dropdown menus to jump directly to any month within a 20-year range.
Clicking on any date reveals a details panel showing the day of the week, day of the year, ISO week number, days remaining until the end of the year, and whether the year is a leap year.
Yes, today's date is highlighted with a blue background so you can quickly identify it. The current month also opens by default when you first load the page.