📅 公历转儒略历日期Convert Gregorian Date to Julian Date
把公历（格里高利历）日期换成同一天的儒略历日期。本地处理。Convert a Gregorian (civil) date to the Julian-calendar date for the same day. Processed locally.
使用说明与常见问题How-to & FAQ
「公历转儒略历日期」是什么？What is the Convert Gregorian Date to Julian Date tool?
把公历（格里高利历）日期换成同一天的儒略历日期。本地处理。Convert a Gregorian (civil) date to the Julian-calendar date for the same day. Processed locally.
如何使用「公历转儒略历日期」？How do I use the Convert Gregorian Date to Julian Date tool?
输入一个公历 YYYY-MM-DD 日期，下方会显示同一天在儒略历上的日期。Enter a Gregorian date as YYYY-MM-DD to see the same day on the Julian calendar.
儒略历日期和儒略日有什么不同？How is a Julian calendar date different from a Julian day?
本页输出的是儒略历（公元前 45 年开始使用的旧历法）上的年-月-日，例如 2026-10-20 在儒略历上是 2026-10-07。儒略日 JDN 则是天文用的连续整数日编号，用「日期转儒略日」工具计算。This page gives the year-month-day on the Julian calendar, the older calendar introduced in 45 BC — 2026-10-20 is 2026-10-07 there. A Julian Day Number is a different thing: a continuous integer day count used in astronomy, available in the Convert Date to Julian Day tool.
用的是哪种历法？和时区有关吗？Which calendar is used, and do time zones matter?
所有日期都按外推格里高利历（proleptic Gregorian，即把现行公历规则向前一直沿用）计算，年份 0000–9999，0000 年即公元前 1 年。1582 年 10 月 5 日到 14 日在历史上采用格里高利历时被跳过，从未实际存在；页面仍按外推公历计算这些日期，并在结果下方给出提示。计算只用你输入的日期，不读取设备时钟，所以时区和夏令时不影响结果。输出的年份总是 4 位（如 0005-06-07）。All dates are proleptic Gregorian: today's calendar rules applied backwards without a break, for years 0000–9999 (year 0000 is 1 BC). The days 1582-10-05 to 1582-10-14 never existed in the Gregorian calendar as historically adopted — they were skipped — so the page still computes them as proleptic dates but shows a note below the result. Only the dates you type are used and the device clock is never read, so time zones and daylight saving time do not affect the result. Years are always printed with 4 digits, e.g. 0005-06-07.
输入和输出是什么样的？What does the input and output look like?
例如在「公历转儒略历日期」中输入 2020-01-14，输出为：2020-01-01。For example, the Convert Gregorian Date to Julian Date tool turns the input 2020-01-14 into: 2020-01-01.
「公历转儒略历日期」免费吗？需要注册吗？Is the Convert Gregorian Date to Julian Date tool free? Do I need an account?
「公历转儒略历日期」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Convert Gregorian Date to Julian Date tool is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.