Day of the Week CalculatorFree online other calculator — instant results, no sign-up
Which weekday a date falls on.
About the Day of the Week Calculator
The Day of the Week Calculator determines the specific day of the week (such as Monday, Friday, or Sunday) for any chosen calendar date. It is useful for planning events, checking historical days of birth, or verifying schedules without manually navigating a multi-year calendar.
- Date
- The calendar date to check, entered in standard YYYY-MM-DD format.
Formula and method
Day = Weekday(Date at 00:00:00 local time)
- DateThe specified calendar day (year, month, and day)
- WeekdayThe localized weekday name (e.g., Sunday through Saturday) corresponding to the date
The calculator parses the input string into a standard date object set to midnight (00:00:00 local time). It then formats the date using the en-US locale to extract the full weekday name alongside a standardized short-form date representation.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Date1970-01-01
Results
- DayThursday
- DateThu, January 1, 1970
How to use the Day of the Week Calculator
- 1Select or input the target calendar date (YYYY-MM-DD).
- 2Parse the date at midnight local time to avoid timezone offset shifts.
- 3Evaluate the weekday corresponding to that calendar position.
- 4Output the full weekday name along with the formatted calendar date.
Reading your result
The primary output displays the full weekday name (e.g., 'Friday'). The secondary output presents the full date formatted with the abbreviated day, month, day of the month, and four-digit year for clear confirmation.
Limitations
The calculator relies on standard Gregorian calendar projections for both past and future dates. It does not account for the historical Julian-to-Gregorian transition dates that occurred variably across different countries prior to the 20th century.
Common questions
Can I look up the day of the week for historical dates like my birthday?+
Yes, you can enter past dates to find out what day of the week an event or birth took place.
Why does the date string include 00:00:00 in the code?+
Specifying midnight local time prevents the browser from interpreting the date as UTC, which can inadvertently shift the result backward by one day in negative UTC offset timezones.
Does this tool work for dates hundreds of years in the past?+
It applies the proleptic Gregorian calendar backward. Historical events recorded under the Julian calendar before 1752 (in Britain and its colonies) or 1582 (in Catholic Europe) may differ by several days.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
Further reading
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Results are estimates for informational purposes and are not financial, medical or legal advice.