“Divisible by 4” is only part of the leap year rule — century years like 1900 break that pattern, and centuries divisible by 400 like 2000 break it again. This tool checks any year instantly and explains exactly which part of the rule applied.
What Is the Leap Year Checker?
Enter any year and see immediately whether it’s a leap year, along with a plain-English explanation of which rule determined the answer (the basic divisible-by-4 rule, the century exception, or the exception-to-the-exception for years divisible by 400) — plus a quick visual list of nearby leap years.
How to Use It
- Open the tool at /tools/leap-year-checker.
- Type in any year.
- Read the leap year verdict and the explanation of why.
- Scan the nearby leap years list to see the surrounding pattern.
Key Features
- Full Gregorian calendar rule, including the century exception and its own exception.
- Plain-English explanation for every result, not just a yes/no answer.
- Nearby leap years shown, making the usual 4-year (or occasional 8-year, around non-leap centuries) pattern visible at a glance.
- Works for any year, from ancient history to the far future.
When to Use This Tool
- Writing or debugging date-handling code that needs correct leap year logic.
- Quickly checking historical or future years (like century years) that are easy to get wrong by hand.
- Teaching or learning the actual leap year rule, beyond the oversimplified “every 4 years” version.
Try It Now
Open Leap Year Checker directly, or press ⌘K and type the tool name from anywhere on the site.
Part of the Date & Time collection on WebdevToolbox — free, browser-based developer tools with no login required.