Leap Year Calculator [2025]
Instantly check if any year is a leap year. Enter a year to see if it has 366 days.
What is a Leap Year?
A leap year occurs every 4 years to help synchronize the calendar year with the solar year, or the length of time it takes the Earth to complete its orbit around the sun (approximately 365.2425 days).
To account for this fractional day, an extra day – a leap day (February 29th) – is added to the calendar during a leap year. This makes the year 366 days long instead of the usual 365.
The Rules for Leap Years:
- A year is a leap year if it is evenly divisible by 4.
- However, if a year is divisible by 4 and also divisible by 100, it is NOT a leap year.
- Unless the year is also evenly divisible by 400. Then it IS a leap year.
Examples:
- 2000: Divisible by 4, 100, and 400 → Leap Year
- 2024: Divisible by 4, not by 100 → Leap Year
- 1900: Divisible by 4 and 100, but not by 400 → Not a Leap Year
- 2023: Not divisible by 4 → Not a Leap Year
- 2100: Divisible by 4 and 100, but not by 400 → Not a Leap Year
Frequently Asked Questions
Why do we need leap years?
Without leap years, the calendar would drift out of sync with the seasons. Over centuries, summer months would eventually occur during winter, and vice versa. Leap years keep the calendar aligned with the Earth's journey around the sun.
Who invented the leap year?
The concept dates back to ancient times, but the system we largely use today (the Gregorian calendar) was introduced by Pope Gregory XIII in 1582, refining the Julian calendar system established by Julius Caesar.
Is every fourth year a leap year?
Almost! The exception is years divisible by 100 but not by 400. For example, 1900 and 2100 are not leap years, but 2000 was.
What are "leaplings"?
People born on February 29th are sometimes called "leaplings" or "leapers." They typically celebrate their birthdays on February 28th or March 1st in non-leap years.
Comments
No comments yet
Be the first to share your thoughts! Your feedback helps us improve our tools and inspires other users.
More Time Tools
Age Calculator
Calculate your age & remaining time on this planet
Age Difference Calculator
Determine difference in ages
Business Day Calculator
Calculate the number of business days between two dates
Chrome Timestamp Converter
Convert Chrome/Webkit timestamps into human readable dates
Clarion Date Converter
Convert between Clarion and human-readable dates
Countdown Timer
Everything you ever wanted in a timer
Date Difference Calculator
Determine the difference between two dates
Date Formatter
Format dates in all kinds of ways
Discord Timestamp Converter
Convert any date to Discord's own format
DMESG Timestamp Converter
Convert Linux DMESG dates to human readable ones
JSON Timestamp Converter
Convert JSON dates to standard formats
LDAP Timestamp Converter
Convert LDAP to human readable dates
MongoDB Timestamp Converter
Convert ObjectIDs to human readable dates
NTP Timestamp Converter
Convert between NTP format and regular timestamps
Pomodoro Timer
Use this famous focus technique to your advantage
Retirement Calculator
Calculate the time until you reach retirement
Roman Date Converter
Convert between Roman and Gregorian dates
SQL Timestamp Converter
Convert between different date formats in SQL Server
Time Unit Converter
Convert from miliseconds all the way to years
Timezone Converter
Travel across the globe with our timezone converter
Week Number Calculator
Find out what week number a specific date has
Windows Timestamp Converter
Convert Integer8 to human readable dates
Work Hours Calculator
Calculate your work hours over a given time period