Find the ISO week number for any date. Free ISO 8601 week calculator.
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Quick answers to common questions
Uses the ISO 8601 standard where week 1 contains the first Thursday of the year.
Yes. 100% free with no signup. All calculations run in your browser.
Yes. Nothing is sent to any server.
Yes. All date and time tools are mobile-friendly.
Your data is processed entirely in your browser. Nothing is sent to any server.