What WeekYear is
WeekYear started with one question — what week is it right now? — and grew into a complete reference for the week as a unit of time. The homepage answers the original question live, by ISO 8601 rules, in your time zone. Around it sit the tools and references people ask for next:
- Week number charts for every year, with exact Monday–Sunday dates and a page for every individual week 1–53.
- Calculators — date to week number, week number to dates, and weeks between dates.
- Printable one-page week calendars for wall planning.
- Guides covering the ISO 8601 standard, week codes and formats, Sunday-vs-Monday conventions, spreadsheet formulas, fiscal 4-4-5 calendars, payroll, and sprint planning.
Who it is for
Anyone who works in weeks: operations and logistics teams scheduling by week code, engineers and product teams running sprint cadences, finance and payroll teams handling 53-week years, marketers planning publication weeks, and individuals doing weekly reviews or 12-week goals. It is also for the moment a colleague in another country says "delivery in KW 34" and you need to know what days that actually is.
Accuracy
All week numbers on this site follow ISO 8601 — weeks start on Monday, week 1 contains January 4 — and are computed with standard library calendar functions, not lookup tables. The live values on each page are calculated in your browser from your device's clock, so they are correct in your time zone. Where other conventions exist (US Sunday-start numbering, fiscal calendars), pages say so explicitly and show how the systems differ. Spotted something wrong anyway? Tell us — corrections are the fastest category of email we answer.
How the site is funded
WeekYear is free to use, with no accounts or sign-ups, and is supported by advertising (Google AdSense) and analytics as described in the privacy policy and cookie policy.