What is the Gregorian leap year rule?

A year is a leap year if it is divisible by 4, EXCEPT for years divisible by 100 — which are NOT leap years — UNLESS they are also divisible by 400, in which case they ARE leap years. So 1900 is not a leap year but 2000 is.

Why do we need leap years?

The Earth takes approximately 365.2422 days to orbit the Sun. Without leap years, the calendar would drift by about one day every four years, eventually misaligning seasons with calendar months.

Was the year 1900 a leap year?

No. 1900 is divisible by 100 but not by 400, so it is a common year with 365 days.

Was the year 2000 a leap year?

Yes. 2000 is divisible by 400, which overrides the century exception, making it a leap year with 366 days.

Can this tool handle years before the Common Era?

Yes. Enter negative integers (e.g. -44 for 44 BCE). The same Gregorian rules are applied, though the Gregorian calendar was only officially adopted in 1582.

What is the next leap year?

Starting from any year, the tool will tell you whether that year itself is a leap year. For 2024 the answer is yes; 2025, 2026, and 2027 are not; 2028 is.

Leap Year Checker

Name: Leap Year Checker
Availability: InStock
Author: Nham Vu

Enter any year to instantly find out if it is a leap year, with a clear explanation of why.

Enter a Year

Quick examples

Enter a year and click Check Year to see the result.

Summary

Enter any year to instantly find out if it is a leap year, with a clear explanation of why.

How it works

Type any year (positive or negative) into the input field.
The tool checks whether the year is divisible by 4.
If divisible by 4, it checks whether the year is also a century (divisible by 100).
If it is a century, it checks whether the year is divisible by 400.
Each step is highlighted so you can follow the exact rule path.
The final verdict — Leap Year or Common Year — is displayed prominently.

Use cases

Verify whether February 29 exists in a given year for date calculations.
Teach students the Gregorian leap year algorithm step by step.
Debug calendar logic in software that handles date arithmetic.
Quickly settle disputes about years like 1900 (not a leap year) vs 2000 (a leap year).
Plan events that fall on February 29.
Cross-check date validation rules in spreadsheets or code.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu