Day of the Week Calculator
Find out what day of the week any date falls on — past or future — plus the day of year, week number and how long ago or away it is. Great for birthdays. Free, private.
Last reviewed by the Radiatus Cloud team
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Find the day of the week for any date
Which day of the week a date falls on, past or future, is often useful and not easy to work out mentally. This calculator finds the day of the week for any date, plus related information.
Why the day of the week is not obvious
The day of the week for a date follows a pattern but not a simple one, because of the varying month lengths and leap years, so working it out in your head for an arbitrary date is genuinely hard. Knowing the day for a past date, what day were you born, or a future one, what day will a date fall on, is a common curiosity and a practical planning question. The calculator computes it correctly for any date, near or far, past or future.
A calculation, not advice
It runs entirely in your browser, so nothing you enter is uploaded and it works without an account, keeping your figures on your own machine.
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Frequently Asked Questions
How does it find the day of the week?
By computing it from the date using the calendar rules, accounting for month lengths and leap years, for any date past or future.
Why is this hard to do mentally?
Because the day follows a pattern complicated by varying month lengths and leap years, so working it out for an arbitrary date in your head is difficult.
Can it handle any date?
Yes. It works for dates far in the past or future, not just those near today.
What is it useful for?
Curiosity, such as the day you were born, and planning, such as which day a future date falls on.
Is my data uploaded?
No. The calculation runs entirely in your browser.
Privacy & Security
All processing happens locally in your browser — nothing is uploaded.
How to Use
Pick any date to see which weekday it is (or was) and related facts.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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