Date & Time
Age, duration & timezone calculators
Current Week Number (ISO-8601)
Find the current ISO-8601 week number, plus the week’s Monday-to-Sunday date range and the ISO year. Weeks start on Monday and week 1 is the week that contains the year’s first Thursday — equivalently, the week that contains January 4 — which is the international standard used across Europe and in business, manufacturing and logistics. Enter today’s date (or any date) and read off the week number: for example 1 January 2026, a Thursday, is ISO week 1 of 2026. Because the “current” week depends on your local date, the answer follows the date you enter rather than a fixed timezone. Everything is computed in your browser, and the result matches Excel and Google Sheets ISOWEEKNUM() rather than the older Sunday-start WEEKNUM default.
ISO week = the Thursday-anchored week number (Monday-start; week 1 contains Jan 4)
- 1 Jan 2026 (Thursday) = ISO week 1 of 2026
- Also shown: the ISO year and the week’s Monday–Sunday date range
Frequently asked questions
What week number is it right now?
Enter today’s date and read the ISO-8601 week number. The tool shows the ISO week (1–53), the ISO year, and the week’s Monday-to-Sunday range. The current week follows your local date, so the answer tracks the date you enter.
Does this match the week number in Excel?
Yes — it matches ISOWEEKNUM() in Excel and Google Sheets. If your spreadsheet shows a different number it is using WEEKNUM with a Sunday-start return_type; use WEEKNUM(date, 21) or ISOWEEKNUM to reproduce the ISO answer.