Leap Year Checker
About this Tool
The Leap Year Checker on AllThatConverter instantly tells you whether any year is a leap year or a common year, explains the divisibility rule (by 4, by 100, by 400), and shows how many days February has that year. It also finds the nearest previous and next leap years, and can list every leap year within a custom year range.
Processed safely on your device
Everything happens in your browser on this device. Your files are never sent to our servers—so you can use it with peace of mind.
How to Use
Type a year into the input field, or click 'This year' to load the current year.
The result appears instantly: leap or common year, February's day count, the rule explanation, and the nearest previous/next leap years.
Open 'Find leap years in a range' and enter a start and end year to list every leap year in that span.
Key Scenarios & Use Cases
Planning a Feb 29 birthday or anniversary
People born on February 29 don't have a real birthday on common years — quickly check when the next leap year falls to plan a celebration.
Verifying date logic in calendar, payroll, or accounting software
Developers can cross-check their own leap year implementation against the century (100) and quadricentennial (400) exceptions.
Counting leap years across a historical or statistical range
Use the range search to instantly count how many leap years occurred within a given span of years.
Frequently Asked Questions (FAQ)
A year is a leap year if it's divisible by 4. However, if it's also divisible by 100, it is NOT a leap year — unless it's also divisible by 400, in which case it is. For example, 2000 is a leap year, but 1900 is not.
To protect browser performance, the range search is capped at 200 years per query. Wider ranges are automatically clamped to the first 200 years from the start year, with a note shown.