Last updated October 13, 2026 · Report an error
Every calendar date falls on exactly one day of the week — but figuring out which one by hand, especially for a date far in the past or future, isn't straightforward.
This calculator instantly finds the day of the week for any date, along with its day-of-year and week number.
How it works
Enter any date, past or future. The calculator uses standard calendar arithmetic to determine which day of the week it falls on, along with which day of the year and which week of the year it is.
- Enter date.
- Click Calculate to see your results.
Examples
A historical date
July 4, 1776 fell on a Thursday.
Who should use it
- Finding what day of the week you were born.
- Checking what day of the week a historical or future date falls on.
Industry applications
- Event and calendar planning
- Historical and genealogical research
Advantages
- Works for any date, not just recent or upcoming ones.
- Also reports the day of the year and week number.
Limitations
- Uses the modern Gregorian calendar — very old historical dates before its adoption may fall under a different calendar system in original records.
Common mistakes to avoid
- Assuming a date always falls on the same day of the week each year — it shifts by one day each year (two after a leap year).
- Trying to calculate dates before the Gregorian calendar was adopted in a given region, which can produce inconsistent results across historical calendar systems.
Best practices
- For planning recurring events, remember that a specific date (like "the 15th") doesn't stay on the same weekday year to year — use "the third Monday" style scheduling if a consistent weekday matters.
Tips
- A given date shifts one weekday later each year, except after a leap year, when it shifts two — a quick mental shortcut for estimating nearby years.
Frequently asked questions
Yes, with no signup and no limit on how many calculations you run.
Yes — the calculator uses the standard Gregorian calendar, which is valid for calculating any date within the calendar system's range.
It's the date's position counting from January 1st — for example, February 1st is day 32.
It follows the standard ISO week numbering convention, where week 1 is the week containing the year's first Thursday.