Leap Years & Days per Year (1800–2100)
Current year: Leap years satisfy: divisible by 4 but not by 100, or divisible by 400.
| Year | Days | Type | ISO week start |
|---|
うるうYear＆YearあたりのDay数（1800–2100）
Leap-year rule: divisible by 4 but not by 100, or divisible by 400. Such years have 366 days with 29 days in February; the rest are common years with 365. This table lists every year from 1800 to 2100 for quick checking.
Data is computed locally in your browser.
Features
- Three-century span — Covers 1800–2100, enough for almost all historical and future date checks.
- Leap flag — Each year is marked "Leap / Common" with its day count.
- ISO start week — Shows which ISO week the first week of each year starts at.
How to use
- The page shows the full leap-year table on open, with the current year highlighted.
FAQ
Why is 1900 not a leap year?
The leap rule has an exception: a year divisible by 100 must also be divisible by 400 to be a leap year. 1900 is divisible by 100 but not by 400, so it is a common year; 2000 is divisible by 400, so it is a leap year.