What week of the year is it?

Today, Friday, October 2, 2026, is in week 40 of 2026 by the ISO 8601 standard, the one used in most of the world for planning, payroll and logistics. This week runs from Monday, September 28, 2026, to Sunday, October 4, 2026. The year has 53 ISO weeks, and today is day 275 of 365.

Today in numbers

All weeks of 2026

Each week runs from Monday to Sunday. The current week is highlighted.

ISO 8601 versus the US and Brazilian numbering

Most countries in Europe, Asia and Latin America, and most companies that work internationally, follow ISO 8601: weeks start on Monday, and week 1 is the one that contains the first Thursday of the year. The United States, Canada and Brazil's everyday calendars start the week on Sunday, and many spreadsheets, including Excel's default WEEKNUM, count the week that contains January 1 as week 1, even if it has a single day in it. The two systems can disagree by one week, or even put the same date in different years, so always say which one you mean. In Brazil's health system the epidemiological week also runs from Sunday to Saturday.

Why week 1 always contains January 4

ISO 8601 wants every week to belong entirely to one year, and to the year that holds most of its days. A week that has its Thursday in the new year has at least four of its seven days there, so it is week 1. This is the same as saying that week 1 is the week with January 4. As a consequence, the first days of January can belong to the last week of the previous year (January 1, 2027 is in week 53 of 2026), and the last days of December can belong to week 1 of the next year (December 29, 2025 is already week 1 of 2026).

Years with 53 weeks

A year has 364 days in 52 weeks, plus one or two extra days. Every five or six years, the extra days add up to a 53rd week. In ISO terms, a year has 53 weeks if January 1 falls on a Thursday, or on a Wednesday in a leap year. Recent and upcoming examples are 2015, 2020, 2026 and 2032. This matters for payroll, production schedules, school calendars and any report that compares week by week, because week 53 has no counterpart in a normal year. 2026 has 53 weeks.

Where week numbers are used

Week numbers are common in industrial planning, delivery dates, project schedules and sports seasons, because "week 32" is shorter and less ambiguous than a pair of dates. Combine this page with the days between dates and date calculator tools to measure deadlines, or check the start of the seasons and the Moon phase for the same date range.