A leap year contains 366 days instead of the standard 365 days. An extra intercalary day—February 29—is added to keep our astronomical calendar in alignment with Earth's orbit around the Sun.
The 3 Rules for Identifying a Leap Year
According to the Gregorian calendar system:
- Every year divisible by 4 is a leap year (e.g., 2020, 2024, 2028).
- Exception: Century years divisible by 100 are NOT leap years (e.g., 1900, 2100).
- Exception to the Exception: Century years divisible by 400 ARE leap years (e.g., 1600, 2000, 2400).
When Do "Leaplings" Celebrate Their Birthday?
People born on February 29th (often called "leaplings") face a unique question during non-leap years. In common years with only 28 days in February, legal jurisdictions and individuals generally celebrate on one of two days:
February 28th vs. March 1st
February 28th: Celebrating on the last day of February maintains the birth month.
March 1st: In many legal codes, official age advancement for February 29th births occurs on March 1st in non-leap years because 365 full days have elapsed.
How myagenow Handles Leap Years
Our exact age algorithm dynamically checks whether a target or birth year is a leap year. For February 29th birth dates during common years, birthday countdowns evaluate accurately to February 28th to ensure your age readout remains 100% precise.