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Leap Year Calculator

Check whether a Gregorian calendar year contains February 29 and 366 days.

Date conventions explained belowClear start and end values

Set your dates & time

Runs on your device

TIME SUMMARY

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter year.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

A year is a leap year if divisible by 4, except years divisible by 100 unless they are also divisible by 400.

A WORKED EXAMPLE

2000 is a leap year because it is divisible by 400. 1900 is not a leap year, although it is divisible by 4.

What to keep in mind

Applies Gregorian rules consistently to years 0100–9999. Historical adoption dates differed by country; this is not a historical local-calendar reconstruction.

Common questions

Why are some century years not leap years?

The Gregorian rule omits three leap days in every 400-year cycle by excluding century years not divisible by 400.

How many days are in February?

29 in a Gregorian leap year and 28 otherwise.

Methodology maintained by ClarityKit. How these tools are built and checked.