Leap year calculator
Find whether a year has 365 or 366 days.
Formula
Leap if divisible by 4, except by 100 unless also by 400. Days = 365 + leap; February = 28 + leap, with leap = 1 or 0.
Days in year ≈ 365+(1) · Days in February ≈ 28+(1)
How to use
- Enter a whole year from 1583 to 9999.
- Read the leap or common year result.
- Check the year and February day counts.
Examples
- 2024: leap, 366 days, February 29 days. 2100: common, 365 days, February 28 days.
Reference table
| Range | Category |
|---|---|
| 0 ≤ x < 1 | common |
| 1 ≤ x < 2 | leap |
Frequently asked questions
Is 2024 a leap year?
Yes. It has 366 days, including 29 in February.
Why is 1900 common but 2000 leap?
Century years must be divisible by 400; only 2000 meets that rule.
Which calendar is used?
Gregorian only. Local historical calendar changes and lunar leap months are not modeled.
Sources
Updated: