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What this calculator does
Find the weekday for any calendar date.
How to use this calculator
- Enter the date you want to check.
- Review the calculation assumptions before using the result.
- The result identifies its day of the week.
How to calculate
Choose the calculation mode where available, then enter the values requested by the day of week calculator. Results update immediately.
Worked example
With the example values shown above, the day of the week is Saturday, and the ISO week number is 34, and the day of year is 234.
Understanding your result
The result identifies its day of the week.
- Use the correct calendar date and locale.
- Double-check values and units before calculating.
Frequently asked questions
What does this day of week calculator do?
Find the weekday for any calendar date.
How do I use this day of week calculator?
Enter the date you want to check.
What does the result mean?
The result identifies its day of the week.
What should I check before relying on it?
Use the correct calendar date and locale.
What is the ISO week number?
It's the week's position in the year under the ISO 8601 standard, where week 1 is the week containing the year's first Thursday — this can differ from simply dividing the day of year by 7, especially near the start or end of the year.
Does this work for historical or far-future dates?
Yes — enter any valid calendar date and it calculates the weekday, ISO week number, and day of year using standard Gregorian calendar rules.