A leap year is a year with 366 days instead of 365. The extra day, February 29, is added every four years to keep the calendar synchronized with Earth's orbit around the Sun.
Why Do We Need Leap Years?
Earth takes approximately 365.2422 days to orbit the Sun — not exactly 365. Without leap years, the calendar would drift about 6 hours per year, meaning after 100 years, January would fall in what is now autumn in the Northern Hemisphere.
Leap Year Rules
A year is a leap year if it meets these conditions:
- Divisible by 4 — the basic rule
- Exception: If also divisible by 100, it is NOT a leap year
- Exception to the exception: If divisible by 400, it IS a leap year
Recent and Upcoming Leap Years
- 2024 ✓ (divisible by 4)
- 2028 ✓
- 2032 ✓
- 2100 ✗ (divisible by 100, not 400)
- 2400 ✓ (divisible by 400)
February 29 in Countdowns
HowUntil automatically accounts for February 29 in all date calculations. If your countdown spans a leap day, the extra day is included.
Put It Into Practice
Use our free, instant calculator tools to run these calculations on your exact dates without any manual math.