What Is a Weekday Calculator?
A Weekday Calculator determines which day of the week corresponds
to a specific calendar date. Enter a date and the calculator
identifies whether it falls on Monday, Tuesday, Wednesday,
Thursday, Friday, Saturday, or Sunday.
The tool also provides additional calendar information such as
the day number, day of the year, ISO week number, leap year
status, and whether the selected date is a weekday or weekend.
Example:
Select September 19, 2026 and the calculator determines the
weekday associated with that calendar date.
How to Use the Weekday Calculator
Finding the weekday for a date takes only a few seconds.
1
Select a Date
Choose the calendar date you want to check using
the date field.
2
Find the Weekday
Click the Find Weekday button to process your
selected date.
3
View Date Details
See the weekday plus week number, day of year,
month, year, and other details.
Days of the Week
A standard seven-day week contains five days commonly treated
as weekdays and two days commonly treated as weekend days.
Work schedules can differ between locations and organizations.
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
What Information Does the Calculator Show?
Day of the Week
The main result shows the weekday name associated with
the selected calendar date.
Day Number of the Week
The calculator numbers the week from Monday through Sunday,
with Monday shown as day 1 and Sunday as day 7.
Day of the Year
This tells you how far the selected date is into its calendar
year. January 1 is day 1, while the final day is day 365 in
a standard year or day 366 in a leap year.
ISO Week Number
The ISO week number identifies which numbered week of the
year contains the selected date according to the ISO week-date
system.
Leap Year Status
The tool checks whether the selected year contains 365 or
366 days and displays whether it is a leap year.
Common Uses of a Weekday Calculator
Finding the weekday of a particular date can be useful for
both historical dates and future planning.
-
Check which weekday a birthday falls on.
-
Find the weekday of a historical event.
-
Plan meetings, appointments, or events.
-
Check future calendar dates.
-
Verify dates in records and schedules.
-
Determine whether a date falls on a weekday or weekend.
-
Find ISO week numbers for planning and reporting.
-
Check leap-year information.
How Does a Leap Year Affect Weekdays?
A standard calendar year has 365 days, while a leap year has
366 days. The extra day is February 29.
Because 365 is one day more than exactly 52 weeks, the weekday
for a particular calendar date normally shifts from one year
to the next. Leap years can create an additional shift for
dates after February.
Leap Year Rule:
A year is generally a leap year when it is divisible by 4.
Century years must also be divisible by 400 to remain leap years.
Frequently Asked Questions
What does a Weekday Calculator do?
It finds which day of the week corresponds to a selected
calendar date.
Can I find the weekday of a past date?
Yes. You can select a supported historical date and the
calculator will determine its weekday.
Can the calculator check future dates?
Yes. The tool can calculate the weekday for supported
future dates as well as current dates.
What is the day number of the week?
This calculator uses Monday as day 1, Tuesday as day 2,
and continues through Sunday as day 7.
What is an ISO week number?
An ISO week number identifies a week within the ISO week-date
calendar. ISO weeks begin on Monday.
Does the calculator identify leap years?
Yes. The result includes whether the selected calendar year
is a leap year.
Is Saturday a weekday?
In the common Monday-through-Friday convention, Saturday
and Sunday are classified as weekend days. Workweek conventions
can vary in practice.