Find the ISO week number, standard week, and full week range for any date
This tool shows two week numbering systems for any date you choose. The Standard Week (used in the US) runs Sunday through Saturday, with week 1 starting on January 1. The ISO Week (ISO 8601, used in Europe and most of the world) runs Monday through Sunday, with week 1 defined as the week containing the year's first Thursday.
The tool also shows the week-of-month number and the exact date range for both week types. All calculations happen in your browser — no data is sent to any server.
Yes, Week Number is completely free to use on UtilityCove.
No. Week Number runs in your browser, so your input stays on your device.
Yes. Week Number works on modern mobile and desktop browsers.
Age Calculator
Calculate exact age in years, months, days, and hours.
Date Calculator
Add or subtract days, weeks, or months from a date.
Business Days Calculator
Calculate working days between two dates.
Date Formatter
Format any date in 12 different patterns.
Unix Timestamp Converter
Convert Unix epoch seconds or milliseconds to readable dates and back.
Time Zone Converter
Convert times between world time zones.