Josh Liljenquist

Date and time utility

Day of Week Calculator

Enter a date to find whether it falls on Monday, Tuesday, or another day of the week. The calculation treats the input as a calendar date, not a time-zone timestamp.

By

Enter values and calculate.

Method

The date is validated in the Gregorian calendar and mapped to a UTC day index. The weekday cycle repeats every seven days, so no local time-zone conversion is needed.

Worked example

July 4, 2026 falls on a Saturday. February 29, 2024 falls on a Thursday.

Limits and assumptions

Supported years are 1600 through 9999 in the proleptic Gregorian calendar. Historical places adopted the Gregorian calendar at different times, so very old local historical records may follow another calendar.

Date and time privacy

All supported calculations run locally with validated text and date-only arithmetic where appropriate. These educational utilities do not send entered values to a server, infer a location, or make professional scheduling decisions for you.

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