About the Week Number
What week is it right now? This page answers immediately, showing the current ISO-8601 week number the moment it loads — no clicking required. You can also look up the week number of any other date, past or future: pick a day and you'll get its week number along with the exact Monday-to-Sunday dates that week covers, so there's never any ambiguity about where a week begins.
Week numbers run business life in much of Europe and in global logistics: deliveries promised for 'week 37', sprints planned by week, factory schedules and school terms all lean on them. The catch is that not every system counts weeks the same way — this tool uses the ISO-8601 standard, where weeks start on Monday and week 1 contains the year's first Thursday, matching what calendars in Europe and most planning software display.
Features
- Shows the current week number the instant you arrive
- Look up the ISO week of any past or future date
- Displays each week's start and end dates
- Follows the ISO-8601 standard used across Europe
- Handles year boundaries and week 53 correctly
- Free, instant and works on any device
How to find the week number of a date
- Open the page — today's week number appears automatically.
- Pick any other date to check its week.
- Read the ISO week number for that date.
- Note the week's Monday start and Sunday end dates.
Frequently asked questions
What week is it today?
The current ISO-8601 week number is displayed on this page and updates automatically, so whatever it shows right now is the answer. ISO weeks run Monday to Sunday, and most European calendars, project plans and logistics schedules use exactly this numbering, so it will match your planner.
How are ISO week numbers calculated?
Under ISO-8601, weeks start on Monday and week 1 is the week containing the year's first Thursday — equivalently, the week that includes January 4th. That means January 1st can belong to week 52 or 53 of the previous year, and December 29–31 can already sit in week 1 of the next.
Why does my calendar show a different week number?
Some systems — notably the default US convention — start weeks on Sunday and call the week containing January 1st week 1. That numbering can differ from the ISO week by one. This tool follows ISO-8601, the international standard; check your calendar app's settings if the two disagree.
How many weeks are in a year?
Most years have 52 ISO weeks, but years that start on a Thursday — or leap years starting on a Wednesday — contain 53. That happens roughly every five to six years. The tool accounts for this automatically, so dates falling in week 53 are always numbered correctly.
Why do businesses use week numbers?
A week number is a compact, unambiguous way to schedule: 'delivery in week 24' pins down one specific Monday-to-Sunday range with no confusion over date formats or time zones. Manufacturing, retail, logistics and agile software teams across Europe plan by week number for exactly that reason.