Is the Week Number Calculator free?

Yes, completely free with unlimited calculations and no registration required. No hidden fees, no trial limits, no account needed.

What is an ISO week number?

The ISO week number is an international standard (ISO 8601) where weeks run Monday-Sunday, with week 1 being the first week containing a Thursday. It's used globally in business, manufacturing, and data management.

How do I find the week number for today's date?

Click the 'Today' button in the calculator, or manually select today's date in the date picker. The ISO week number will display instantly below.

Can the Week Number Calculator work on mobile devices?

Yes, the calculator works on all devices including iPhone, Android smartphones, tablets, and desktop computers. The mobile-responsive design automatically adjusts to your screen size.

What date formats does this tool accept?

The calculator accepts dates via the interactive calendar picker (works all dates 1900-2100) and supports MM/DD/YYYY format for manual entry. It handles leap years and all month variations automatically.

Is my data stored or tracked by Week Number Calculator?

No. All calculations happen entirely in your browser. No dates are sent to servers, stored in databases, or tracked. Your privacy is completely protected.

What's the difference between week number and ISO week number?

ISO week numbers follow international standards (ISO 8601) with weeks starting Monday and week 1 containing the first Thursday. Regular week numbers vary by country and may start on Sunday or Monday.

Can I batch calculate week numbers for multiple dates?

Currently, the calculator processes one date at a time. For bulk conversions, enter dates sequentially and copy each result, or use the manual ISO 8601 formula for multiple dates in a spreadsheet.

online

Week Number Calculator — online

Find the ISO week number for any date.

Date → Week Number

ISO Week Number

Week 22

2026

MondayMon, Jun 1

TuesdayTue, Jun 2

WednesdayWed, Jun 3

ThursdayThu, Jun 4

FridayFri, Jun 5

SaturdaySat, Jun 6

SundaySun, Jun 7

Week Number → Dates

Week #

Year

How to use Week Number Calculator

Enter Your Date

Click the date input field labeled 'Select Date' and choose your desired date using the calendar picker. You can type the date manually in MM/DD/YYYY format or click the calendar icon to browse months and years.

View the ISO Week Number

The calculator automatically displays the ISO week number in the 'Week Number' result box below the input field. The result shows the week number (01-53) and the corresponding ISO year in the format 'Week XX of YYYY'.

Copy or Reference Your Result

Click the 'Copy' button next to the result to copy the week number to your clipboard. Use this information for project planning, international scheduling, or data analysis across different regions.

Frequently Asked Questions

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