Day of the Week Calculator
Find the weekday for any date.
Understanding Day of the Week Calculator
The Day of Week Calculator determines which weekday corresponds to a specific calendar date. Every date in the modern Gregorian calendar falls on one of seven days: Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, or Sunday.
Knowing the day of the week for a particular date can be useful for checking birthdays, planning appointments, organizing events, researching historical dates, preparing schedules, and determining whether a date falls on a weekday or weekend.
Making the inputs meaningful
To use Day of the Week Calculator effectively, enter the values requested by the calculator and keep their units and meaning consistent. The main information requested on this page includes Select a Date. If the calculator offers selectable methods or options, choose the one that matches the question you are trying to answer.
What this calculation can and cannot tell you
The result is calculated from the inputs shown on this page, so it is most useful when you understand what each input represents. Before relying on the number, check the units, the scale of the result, and any assumptions described above the calculator.
About the Day of Week Calculator
The Day of Week Calculator determines which weekday corresponds to a specific calendar date. Every date in the modern Gregorian calendar falls on one of seven days: Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, or Sunday.
Knowing the day of the week for a particular date can be useful for checking birthdays, planning appointments, organizing events, researching historical dates, preparing schedules, and determining whether a date falls on a weekday or weekend.
Because weekdays follow a repeating seven-day cycle, the day associated with a date can be calculated mathematically. The calculation must account for the structure of the calendar, including different month lengths and leap years.
How the Day of Week Calculator Works
Enter any valid calendar date into the calculator. The calculator determines the corresponding weekday and provides additional information about the selected date, including its position within the week, month, and year.
The calculation uses calendar-date rules rather than relying on the user's device calendar display. This allows the weekday to be determined consistently for dates in the past and future.
Example
Date: July 4, 2021
Result:
Day of the Week: Sunday
The Seven Days of the Week
The modern seven-day week consists of Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, and Sunday. The cycle repeats continuously, so every calendar date can be assigned to one of these seven weekdays.
In some countries and applications, Sunday is treated as the first day of the week, while others use Monday as the first day. The weekday itself does not change; only the convention for numbering or displaying the week can differ.
Why Leap Years Matter
Leap years affect weekday calculations because they contain 366 days instead of the usual 365. The additional day is February 29.
Since 366 days equals 52 complete weeks plus 2 additional days, a leap year shifts the weekday pattern for dates following February 29 compared with a common year.
Common Years and Leap Years
A common Gregorian calendar year contains 365 days. A leap year contains 366 days. Under the Gregorian rules, a year divisible by four is generally a leap year, except century years that are not divisible by 400.
For example, 2000 was a leap year because it is divisible by 400, while 1900 was not a leap year because it is a century year that is not divisible by 400.
Day of the Year
The calculator also identifies the selected dates position within its year. January 1 is day 1, while the final day of a common year is day 365 and the final day of a leap year is day 366.
The day-of-year value can be useful when comparing dates within the same year or tracking annual schedules and milestones.
Weekdays and Weekends
In common usage, Monday through Friday are considered weekdays, while Saturday and Sunday are generally considered the weekend.
Weekend definitions can vary by country, organization, or cultural convention. This calculator uses the commonly used Saturday-Sunday weekend convention when identifying whether a selected date falls on a weekend.
Historical Dates and Calendar Systems
The Gregorian calendar is the civil calendar most widely used today. However, it was adopted at different times in different regions. Earlier historical records may have used the Julian calendar or another local calendar system.
Therefore, when researching historical dates, the original calendar system used in the relevant location and period may need to be considered. A modern Gregorian calculation should not automatically be assumed to represent the historical calendar convention.
Finding the Weekday of a Birthday
The calculator can determine the weekday on which any birthday occurs for a specified year. Because weekdays shift from year to year, a person's birthday may fall on a different weekday each year.
For example, a birthday that occurs on a Monday in one year may occur on a Tuesday or another weekday in a later year, depending on the number of days between the two dates and whether a leap year is involved.
Planning Events by Weekday
Knowing the weekday associated with a date can make planning events, appointments, meetings, travel, and other activities easier. It can also help verify whether a particular date falls on a weekday or weekend.
Understanding the Results
The main result identifies the weekday for the selected date. The additional information shows the full calendar date, the day of the month, month number, year, day of the year, and whether the year is a leap year.
The calculator also identifies whether the selected date falls on a weekend under the standard Saturday-Sunday convention.
Frequently Asked Questions
How do I find the day of the week for a date?
Enter the date into the calculator and it will determine the corresponding weekday.
What are the seven days of the week?
The seven days are Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, and Sunday.
Does the calculator work for future dates?
Yes. Any valid calendar date can be entered, including dates in the future.
Does the calculator work for past dates?
Yes. The calculator can determine the weekday for dates in the past as well as modern and future dates.
Does a leap year affect the day of the week?
Yes. The additional February 29 in a leap year changes the weekday sequence for dates that occur after the leap day.
How many days are in a week?
A week contains seven days.
Is Sunday or Monday the first day of the week?
The convention varies by country and calendar standard. The weekday itself remains the same regardless of which day is displayed as the first day of the week.
Can the calculator tell whether a date is a weekend?
Yes. The calculator identifies Saturday and Sunday as weekend days under the standard convention used by the tool.
Can I find the weekday of a birthday?
Yes. Enter the complete birthday date, including the year, to find the weekday on which it occurred.
Limitations of the Day of Week Calculator
This calculator uses the Gregorian calendar for its date calculations. Historical dates may require a different calendar system depending on the location and period being studied.
Week numbering and the definition of the first day of the week can vary between countries and calendar standards. The weekday result, however, remains independent of these display conventions.
Disclaimer
This calculator is intended for informational purposes only. While we strive for accuracy, we cannot guarantee that every result is correct for every situation.