Find the day of the week for any date — past or future — with its day of the year, ISO week number, leap-year status and days left in the year. Runs entirely in your browser — your numbers never leave this device.
The weekday is worked out from a fixed anchor (1 January 1970 was a Thursday) by counting whole calendar days — never from timestamps — so daylight saving and your timezone cannot shift the answer.
| Date | Weekday | Note |
|---|---|---|
| 1 January 2000 | Saturday | The millennium New Year |
| 15 June 1990 | Friday | |
| 29 February 2024 | Thursday | A leap day |
| 1 November 2026 | Sunday | Day 305 of 2026 |
| 2 November 2026 | Monday | Opens ISO week 2026-W45 |
| 30 January 2027 | Saturday | 90 days after 1 Nov 2026 |
Enter any date and the tool names its weekday. The method is pure counting: the date is converted to a day number — days elapsed since a fixed anchor, 1 January 1970, which was a Thursday — and the weekday falls out of dividing that count by 7 and taking the remainder. Because it works on whole calendar days on the proleptic Gregorian calendar, the answer is identical for a date in 1900 or 2100 and never depends on your timezone or on daylight saving.
The result page shows the facts that travel with a weekday: the day of the year (1 to 365, or 366 in a leap year), how many days remain in the year after that date, whether the year is a leap year, and the date's ISO week number. Those four facts answer most follow-up questions — payroll weeks, school terms and project plans are usually specified in exactly these terms.
One honest limit: the Gregorian calendar was adopted in different countries between 1582 and the early 20th century, and this calculator applies it backwards uniformly (the 'proleptic' convention). For dates before your country's adoption, a contemporary source may name a different weekday under the Julian calendar.
Any date the picker accepts — the arithmetic is exact for the whole proleptic Gregorian calendar, centuries in either direction. For dates before the Gregorian calendar was adopted where you live (1582 in much of Catholic Europe, 1752 in Britain and its colonies, later elsewhere), historical records written at the time may use the Julian calendar and name a different weekday.
It is the date's position counting from 1 January as day 1. 1 November 2026 is day 305 of 365, leaving 60 days after it. Contracts, warranties and some payroll systems specify dates this way ('day 305'), and astronomers use the same count as the ordinal date.
That is the ISO-8601 week date: weeks start on Monday and week 1 holds the year's first Thursday. 1 November 2026 is the Sunday closing ISO week 44. The Week Number Calculator has the full explanation and converts in both directions.
No. Weekdays advance one per calendar day, and this tool counts calendar days only. Clock changes move hours around inside a day; they never create or remove a day, so they cannot move a weekday.
Enter your birth date — that is the single most common use of this tool. For example, 15 June 1990 was a Friday. The Age Calculator shows the same fact alongside your age breakdown.
No. The calculation runs in your browser and the date never leaves your device.
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