Day of the Week Calculator
Find the weekday for any date in history or the future, plus which numbered weekday of the month it is.
How it works
weekday from the calendar date · nth = ⌈day-of-month ÷ 7⌉ gives the 1st…5th occurrence in the month
The weekday comes straight from the proleptic Gregorian calendar, so it is correct for any modern date, past or future — useful for settling what day you were born on or planning a date years ahead. The "position in the month" tells you whether a date is, say, the third Monday, which is how many public holidays and recurring meetings are defined. Counting from the end of the month also flags the last Friday or last weekday, common for pay dates.
Worked example
15 Jun 2026 is a Monday. Since 15 = 2×7 + 1, it is the 3rd Monday of June 2026, and with 30 days in the month it is also the 3rd-from-last Monday. It is day 166 of the year.
Frequently asked questions
How is the "3rd Monday" worked out?
Divide the day-of-month by 7 and round up: days 1–7 are the 1st occurrence, 8–14 the 2nd, 15–21 the 3rd, and so on. Many holidays, like US Presidents Day, are defined this way.
Is it accurate for old dates?
It uses the Gregorian calendar for all dates. For dates before a country adopted the Gregorian calendar (1582 onward, later in some places), the local historical weekday may differ.
What counts as a weekend?
Saturday and Sunday, the standard Western working week. Some regions use a Friday–Saturday weekend, which this calculator does not switch to.
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This calculator is for educational purposes. Double-check important results before acting on them.