# Week Number Calculator

> Week number calculator: find the ISO week number for any date, plus its week start and end dates. Free, no signup, runs locally in your web browser now.

- **Canonical URL:** https://boringtoolskit.com/week-number-calculator/
- **Category:** Everyday Calculators
- **Evidence level:** catalogue
- **Reviewed:** July 26, 2026
- **Last verified:** 2026-10-12
- **Privacy:** Inputs and results stay in this browser unless the page clearly labels an external request.

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*Local planning estimate. Verify current terms, rates, and policies before acting.*