Find how many days are in any month

Return the Gregorian month length for a month and the year that controls February.

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ToolDays in Month
Input
Output
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Preview

How it works

A bare month number, YYYY-MM value, or parsed date selects a month and year, and day zero of the following month supplies its last day number. A bare 1–12 month uses the selected year or the current browser year.

  • Year zero is only a sentinel meaning current year for bare month input.
  • YYYY-MM is preferable whenever February must be reproducible.

Worked example

February in Leap Year
Check how many days February has in a leap year
Input
											2024-02
Output
												February 2024: 29 days

When to use this

Billing forms choose a final valid date, date pickers size their day menu, and leap-year tests verify February.

Edge cases

  • February 2000 has 29 days because 2000 divides by 400, while February 1900 has 28.
  • A bare 2 can change with the selected or current year; 2024-02 cannot.
  • A month outside 1–12 is rejected instead of rolling into another year.

References