Day of the Week Calculator
Find what day of the week any date falls on, past or future, plus the day of the year, ISO week number and leap year status.
About the Day of the Week Calculator
Want to know which day of the week you were born on, or what day a future holiday will fall on? Enter any date and this calculator returns the weekday, the day number within the year, the ISO week number and whether the year is a leap year.
How to Use the Day of the Week Calculator
- Select or type a date.
- Press Calculate.
- Read the weekday, day of year and week number in the results.
Formula and How It Works
The weekday is taken from the Gregorian calendar, the same system used by Zeller’s congruence. The ISO week number counts weeks starting on Monday, with week 1 being the week that contains the first Thursday of the year.
Frequently Asked Questions
What day of the week was I born?
Enter your date of birth and press Calculate. The first line of the result shows the weekday.
What is a leap year?
A leap year has 366 days. It occurs every 4 years, except century years that are not divisible by 400. So 2000 was a leap year but 1900 was not.