Check Leap Years
「Check Leap Years」はコード、データと QRに使えるブラウザツールです。入力内容と結果は通常この端末内で処理され、登録は必要ありません。
使い方
使い方
- Choose single year or range mode.
- Enter a whole year, or the start and end years.
- Run the check and review the result locally.
Gregorian rule
A year is a leap year when it is divisible by 4, unless it is a century year; century years are leap years only when divisible by 400. This tool applies that rule to the proleptic Gregorian calendar.
Single years or ranges
Check one year or list every leap year in an inclusive range. Years from 1 through 9999 are accepted, and ranges are limited to 5,000 years so results stay easy to read.
Private browser processing
All validation and calculations happen in your browser. No year or range is sent to a server.
よくある質問
あわせて知りたいこと
Why is 1900 not a leap year?
It is divisible by 100 but not by 400, so the century exception applies.
Why is 2000 a leap year?
It is divisible by 400, so it passes the century exception.
Is the range inclusive?
Yes. Both the start and end years are checked.
Does this use historical calendar dates?
No. It applies the proleptic Gregorian rule consistently to years 1 through 9999.