Weekday Calculator
Find out what day of the week any date falls on — past, present, or future.
Fill in the fields above to see your result instantly.
Enter any date and this weekday calculator tells you which day of the week it falls on — whether it's in the past, today, or the future. It also shows the day's position in the year, its ISO week number, whether the year is a leap year, and how many days away it is from today. Great for finding the day you were born, planning around a future date, or settling a “what day was it?” debate.
How to use the Weekday Calculator
- 1
Enter a date
Defaults to today; pick any date from 1900 onward.
- 2
See the weekday
The day of the week appears instantly, phrased for past, present, or future.
- 3
Check the details
Day of the year, ISO week number, leap-year status, and distance from today.
Examples
Frequently asked questions
How do you work out the day of the week for a date?
Every calendar date maps to exactly one weekday under the Gregorian calendar. The calculator reads that mapping directly from the date you enter, so it's always exact.
What is the ISO week number?
The ISO-8601 week number runs 1–53, with weeks starting on Monday and week 1 being the week that contains the year's first Thursday. It's widely used in business and manufacturing calendars.
Can I find what day I was born on?
Yes — enter your date of birth and the calculator shows the weekday you were born, along with the other date facts.
How is a leap year determined?
A year is a leap year if it's divisible by 4, except century years, which must be divisible by 400. So 2000 was a leap year but 1900 was not.