Next Leap Year Checker

About this tool

Leap Year Checker applies the proleptic Gregorian rule to one positive integer year: a year is a leap year if it is divisible by 4, except century years, which must also be divisible by 400. Enter a year — the field starts on the current year — and click Check to get a clear Yes or No, followed by the next eight leap years after the year you entered. The list skips century years such as 2100 correctly, which makes it handy for planning around February 29 birthdays, testing date code, or checking the century exception. A leap year has 366 days and a 29-day February; other years have 365 days and a 28-day February. The checker does not model historical calendar adoption dates before the Gregorian calendar was used in a particular region, and all calculation runs in your browser.

Why use it

• Instant Yes/No: Enter any positive year and get a clear Leap Year? answer using the full Gregorian rule, including the century exception that trips up simple divide-by-4 checks.

• Next Eight Leap Years: Every check also lists the next eight leap years, which is useful for February 29 birthdays, recurring events, or test fixtures.

• Century Years Handled: 1900 and 2100 are correctly reported as common years and 2000 and 2400 as leap years, and the upcoming list skips non-leap centuries.

• Past and Future Coverage: The checker accepts any positive year — historical dates, the present, and centuries into the future — and applies the same rules.

• Offline, Instant Results: Leap year calculation is pure arithmetic that runs entirely in the browser without any server request or account.

How to use

1. Type a year into the Year field — it starts on the current year
2. Click Check
3. Read the Yes or No answer under Leap Year?
4. Look at the list of the next eight leap years after your year

When it helps

• When a person born on February 29 wants to know which upcoming years have an actual birthday
• When a developer writing date-handling code needs to verify boundary conditions around February 28–29
• When a scheduler needs to confirm whether a February 29 event date is valid in a specific year
• When a student is learning the Gregorian calendar rules and wants to test century years
• When verifying that legacy data containing year values handles the divisible-by-100 century exception correctly

Examples

Tips

• The full Gregorian rule in one sentence: divisible by 4 is a leap year, except divisible by 100 is not, except divisible by 400 is
• Year 2100 is NOT a leap year — it is divisible by 100 but not by 400, so the century exception applies
• People born on February 29 (leaplings) commonly celebrate on February 28 or March 1 in non-leap years
• In JavaScript, new Date(year, 1, 29).getMonth() === 1 returns true only in leap years — a quick programmatic check
• The Julian calendar had no divisible-by-400 override, causing it to drift about 3 extra days per 400 years relative to the Gregorian calendar

Frequently Asked Questions

Glossary

Leap Year

A calendar year containing 366 days rather than 365, with February extended to 29 days. In the Gregorian calendar, leap years occur in years divisible by 4, with exceptions for century years not divisible by 400.

Gregorian Calendar

The internationally used civil calendar introduced by Pope Gregory XIII in 1582. It refined the Julian calendar's leap year rule to keep the calendar year aligned with the tropical (solar) year more accurately.

Julian Calendar

The predecessor to the Gregorian calendar, introduced by Julius Caesar. It adds a leap year every four years without exception, causing it to drift about 11 minutes per year relative to the solar year — roughly one day every 128 years.

Divisible-by-400 Rule

The Gregorian override that makes century years (divisible by 100) into leap years when they are also divisible by 400. Years 1600, 2000, and 2400 are leap years under this rule; 1700, 1800, 1900, and 2100 are not.

Intercalary Day (Feb 29)

An extra day inserted into the calendar to keep it synchronised with the solar year. In the Gregorian calendar this day is February 29, added in leap years. The word intercalary means 'inserted between regular days'.

Tropical Year

The time it takes Earth to complete one full orbit around the sun relative to the vernal equinox — approximately 365.2422 days. The Gregorian calendar's average year of 365.2425 days approximates this closely enough that it drifts by only about 26 seconds per year.