Day of Week Calculator
To find the day of the week for any date, enter the date below. The calculator returns the weekday name (Monday through Sunday), the day-of-year number, and the ISO weekday using the Gregorian calendar, with leap years handled automatically — useful for birthdays, historical dates, and trip planning.
How this day of week calculator works
This page focuses on one narrow task: checking what weekday a single date falls on. It is useful when the real question is "what day was this?" rather than a broader date difference or countdown problem.
Where this weekday page fits
Sources and references
These public references support the weekday lookup intent and date formatting logic behind this page.
Day of week calculator FAQ
- Can I use this to find what day of the week I was born?
- Yes. Enter your birth date and the page will return the weekday for that date.
- Can I check a future date too?
- Yes. The calculator works for past and future dates as long as the calendar date is valid.
- How do I find the weekday from a date?
- Enter the date in the form. The page immediately returns the weekday, the formatted date, and supporting calendar details such as the day of year.
- What is the ISO weekday number?
- ISO weekday numbers run from 1 to 7, where Monday is 1 and Sunday is 7.
- When should I use a date calculator instead?
- Use the general date calculator when your real task is finding the difference between two dates or adding and subtracting time from a base date.
Related date tools
Use the weekday page for single-date lookup, then move to the broader date tools when the task becomes date difference, countdown, or workday logic.