Week Number Calculator
ISO week number for any date, and the dates in any week.
ISO week number
Week 27
of 2026
Day of year
182 of 365
Day of week
Wednesday
Quarter
Q3
ShowHide the working
- 1Wednesday, July 1, 2026 falls in ISO week 27
Formula
ISO 8601 week numberingHow it works
The ISO week number for a date. ISO weeks start on Monday, and week 1 is the one containing the year's first Thursday.
Example
1 July 2026 is in ISO week 27.
About the Week Number Calculator
ISO week number for any date, and the dates in any week. It sits in the Date & Time section of NWS Calc, a free collection of calculators that run entirely in your browser. There is no signup, no paywall and no tracking — open the page, enter your numbers, get an answer.
Frequently asked questions
- Is the Week Number Calculator free to use?
- Yes. Every calculator on NWS Calc is completely free, with no signup, no usage limits and no ads.
- Does my data leave my device?
- No. The Week Number Calculator runs entirely in your browser using JavaScript. Nothing you type is uploaded, logged or stored on a server.
- Can I use the Week Number Calculator on my phone?
- Yes. The page is fully responsive and works in any modern mobile or desktop browser — there is nothing to install.
- What else is in Date & Time?
- Ages, durations, business days, countdowns and time zones. You can browse the full Date & Time category for related calculators.