Calendar Week Calculator
Find the ISO week number for any date
🔒 Files never leave your browser
Date Information
--
ISO Week Number
--
Day of Week
--
Day of Year
--
Quarter
Week View
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Additional Details
Weeks remaining in year --
Days remaining in year --
Leap year --
Days in month --
How to Use Calendar Week Calculator
Enter a date
Pick a date or click "Today".
View week info
See ISO week number, day of week, day of year, quarter.
See week calendar
View a mini calendar showing the full week.
Why Choose AllTools Calendar Week Calculator?
- ✓ 100% free, no account needed
- ✓ ISO 8601 week numbers
- ✓ Day of year shown
- ✓ Quarter shown
- ✓ Mini week calendar
- ✓ No data stored or transmitted
Why Use This Tool
- ★ Instant calculations with no server processing
- ★ Completely free with no usage limits
- ★ No account or registration required
- ★ Handles timezones and daylight saving automatically
- ★ Works on any device with a modern browser
Related Resources
Frequently Asked Questions
What is ISO week numbering? ▼
ISO 8601 defines week 1 as the week containing the first Thursday of the year. Weeks run Monday to Sunday.
Is this private? ▼
Yes. All calculations happen in your browser.
Is there a file size limit? ▼
No strict limit. Processing happens in your browser, so capacity depends on your device memory. Most files work smoothly.
Which browsers are supported? ▼
All modern browsers including Chrome, Firefox, Safari, Edge, and Opera on both desktop and mobile.
Can I use this offline? ▼
Yes. Once the page is loaded, the tool works without an internet connection since all processing is local.
Is my data secure? ▼
Yes. Your data never leaves your browser. Nothing is stored on or transmitted to any server.
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