What Week Is It? Today's Week Number

What week is it today?

The number at the top of this page is today's week number, worked out from your device's date the moment the page opens. It is the ISO 8601 week, the system used in Europe, in most of Asia and in software such as Excel's ISOWEEKNUM, Outlook and many diaries. Just below it you will find the US week number for the same day, the dates of the current week from Monday to Sunday and from Sunday to Saturday, and the number of weeks left in the year. Nothing needs to be typed: open the page and read the answer.

Because the page reads the date on your device, the answer changes by itself at midnight. If the number looks wrong, check the date and time zone on your phone or computer, since a device set to the wrong day will show the week for that day.

How to read the answer

Why the week number can belong to another year

ISO week 1 is the week that contains the year's first Thursday. In maths, with the day of the year as the ordinal and Monday as weekday 1,

$$\text{week} = \left\lfloor \frac{\text{ordinal} - \text{weekday} + 10}{7} \right\rfloor$$

So the last days of December can fall in week 1 of the next year, and the first days of January can fall in week 52 or 53 of the year before. For example, 30 December 2024 was in week 1 of 2025, and 1 January 2027 is in week 53 of 2026. This is normal and is why the page always shows the week-year next to the week number.

Weeks left in the year

The tile "Weeks left after this one" counts the full ISO weeks remaining in the current week-year. Most years have 52 weeks; a year that starts on a Thursday, or a leap year that starts on a Wednesday, has 53.

Privacy

Nothing is uploaded; every calculation runs in your browser and never leaves your device.

Related tools

Pick any other date in the full Week Number Calculator, count the working days left this week with the Business Days Calculator, or see how long until a holiday with the Days Until Calculator.

Frequently asked questions