⏪ 几周前是哪天（以及几周后）Weeks Ago Calculator (and Weeks From Now)
算出某个日期（默认今天）往前或往后若干周（可加零头天数）是哪一天，给出日期、星期几和相隔天数。本地处理。Find the date a number of weeks (plus extra days) before or after a reference date (today by default), with the weekday and the number of days. Processed locally.
使用说明与常见问题How-to & FAQ
「几周前是哪天（以及几周后）」是什么？What is the Weeks Ago Calculator (and Weeks From Now) tool?
算出某个日期（默认今天）往前或往后若干周（可加零头天数）是哪一天，给出日期、星期几和相隔天数。本地处理。Find the date a number of weeks (plus extra days) before or after a reference date (today by default), with the weekday and the number of days. Processed locally.
如何使用「几周前是哪天（以及几周后）」？How do I use the Weeks Ago Calculator (and Weeks From Now) tool?
在「几周前是哪天（以及几周后）」中，填写「周数」、「另加天数（可选）」、「方向」、「参考日期」等参数，结果会随输入实时计算并显示在下方。In the Weeks Ago Calculator (and Weeks From Now): Fill in "Weeks", "Extra days (optional)", "Direction", "Reference date"; results are recalculated instantly as you type.
参考日期默认是哪天？What is the default reference date?
页面打开时自动填入你设备上的今天日期；也可以改成任何日期。When the page opens it fills in today's date from your device; you can change it to any date.
“1 周前”就是 7 天前吗？Is "1 week ago" the same as 7 days ago?
是的，本页 1 周 = 7 天，按日历日计算，与月份长短无关。Yes. Here 1 week = 7 calendar days, regardless of month lengths.
能举个计算实例吗？Can you show a worked example?
例如在「几周前是哪天（以及几周后）」中填 周数 = 4，方向 = 之前，参考日期 = 2026-10-21，结果区显示：日期：2026-09-23；星期：星期三；相隔天数：28；ℹ 4 周之前For example, entering Weeks = 4, Direction = Ago, Reference date = 2026-10-21 in the Weeks Ago Calculator (and Weeks From Now) gives: Date: 2026-09-23; Weekday: Wednesday; Days apart: 28; ℹ 4 weeks before the reference date
哪些输入会被检查？Which inputs are validated?
「几周前是哪天（以及几周后）」会检查这些输入——「周数」：必须填写，须为不小于 0且不大于 10,000的整数；「另加天数（可选）」：可留空；填写时须为不小于 0且不大于 6的整数；绝对值超过 10¹⁵ 的数也会被拒绝。不符合时结果区显示具体提示，不会给出数字。The Weeks Ago Calculator (and Weeks From Now) checks its inputs — "Weeks": required, must be at least 0 and at most 10,000 (a whole number); "Extra days (optional)": optional; if given it must be at least 0 and at most 6 (a whole number); numbers above 10¹⁵ in absolute value are rejected too. When a value fails, the result area names the problem instead of showing a number.
有哪些选项可以调整？What options can I adjust?
「几周前是哪天（以及几周后）」的设置：「周数」默认 4；「另加天数（可选）」可留空；「方向」可选 之前、之后（默认 之前）；「参考日期」可留空。每次生成结果都按当前设置处理。Settings in the Weeks Ago Calculator (and Weeks From Now) — "Weeks" default 4; "Extra days (optional)" optional; "Direction": Ago, From now (default Ago); "Reference date" optional. The result always uses the current settings.
时区如何处理？How are time zones handled?
「几周前是哪天（以及几周后）」按日历日期计算，只有“今天”取自你设备的本地日期；计算不涉及钟点，所以时区和夏令时不影响结果。The Weeks Ago Calculator (and Weeks From Now) works with calendar dates; only "today" comes from your device's local date. No clock times are involved, so time zones and daylight saving time do not affect the result.
「几周前是哪天（以及几周后）」免费吗？需要注册吗？Is the Weeks Ago Calculator (and Weeks From Now) free? Do I need an account?
「几周前是哪天（以及几周后）」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 Weeks Ago Calculator (and Weeks From Now) is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.