Day of Week Calculator

A calendar date and its weekday

Use this lookup to check a birthday, anniversary or planned event. It takes one Gregorian date and returns that date with the weekday in the page language. The calculation runs in your browser.

Examples

• 2026-07-04 is Saturday.
• 2000-02-29 is Tuesday; 2000 is a leap year.
• 0001-01-01 is Monday under the proleptic Gregorian convention.

Calendar convention

The Gregorian rules also apply to dates before their historical local adoption. The result does not reconstruct Julian calendars or local calendar reforms. It reads a calendar date without a time of day; the same selected date has the same weekday across device time zones. A day historically skipped in a region still has its proleptic Gregorian weekday in this lookup.

Questions

Will an impossible date roll into the next month?

No. Dates such as 1900-02-29 do not exist in this calendar. The date picker may prevent such input; a blank or invalid value produces an error when queried.

Does the result tell me whether a business is open?

It identifies the weekday only. Holidays, working-day calendars and business opening hours require the applicable local rules.