What day was it
Type any date and we will tell you which weekday it fell on, how many days that is from today, and a curated list of famous moments that also landed on the same weekday.
Tuesday, August 4, 2026
Tuesday
Romans called this dies Martis
Days from today
0
It's today.
ISO weekday
2
Monday = 1, Sunday = 7
Era
Modern
Gregorian calendar, no caveats.
Curated moments that also landed on a Tuesday.
World Wide Web went public
CERN, Geneva
1991-08-06
9/11 attacks on the World Trade Center
New York
2001-09-11
The Gregorian calendar repeats every 400 years, so once you know the anchor day for any year you can derive every other date in that year with simple arithmetic. Mathematicians like Zeller and Conway have published one-line formulas for this; modern browsers expose the same answer through their Intl date APIs. We use the browser's calendar engine so the answer matches whatever localised conventions you have set on your device. The math is faithful all the way back to the year 1, using what historians call the proleptic Gregorian calendar (the Gregorian rules projected backwards across centuries that actually used the Julian calendar).
The Gregorian calendar was introduced in 1582 to fix a slow drift in the Julian calendar. Different countries adopted it at different times: Britain not until 1752, Russia not until 1918. If you are looking up the weekday for a date in, say, the Battle of Hastings, the answer this calculator gives you is on the proleptic Gregorian calendar, which is what most modern history textbooks use. For dates after the relevant country adopted the Gregorian calendar, the weekday matches what locals actually called the day. For older dates, scholars sometimes prefer the Julian-calendar weekday for cultural fidelity; we do not show that here, but it differs by a small offset that grows by one day every century.
The Romans named the seven weekdays after the seven planets they could see in the sky: Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn. The Latin name appears at the top of every result on this page. If you want to keep exploring, the days between dates tool tells you the exact gap between any two dates, and the week number calculator shows the ISO or US week for the same date.
A common year is 52 weeks plus one day, so any fixed date lands one weekday later than it did the year before; when a 29 February sits in between, it jumps two. That is the whole reason a birthday appears to wander through the week. Between 1901 and 2099 the pattern repeats every 28 years, so 1998 and 2026 share every single weekday and an old 1998 calendar is correct again in 2026. Across the full Gregorian system the true repeat takes 400 years, because 400 years hold exactly 146,097 days and that number divides by seven with nothing left over.
If you are testing a mental algorithm such as Conway's Doomsday rule, it helps to have famous dates whose weekdays are thoroughly documented. These six are drawn from the same events list the result card uses.
| Date | Event | Weekday |
|---|---|---|
| 4 July 1776 | Adoption of the US Declaration of Independence | Thursday |
| 17 December 1903 | First powered flight at Kitty Hawk | Thursday |
| 28 August 1963 | March on Washington | Wednesday |
| 20 July 1969 | Apollo 11 lands on the Moon | Sunday |
| 9 November 1989 | The Berlin Wall opens | Thursday |
| 11 September 2001 | Attacks on the World Trade Center | Tuesday |
The picker accepts any date from the year 1000 to 9999. Results before 1900 are flagged as historical because they rely on the proleptic Gregorian calendar rather than the calendar people were using at the time.
Older sources often date events on the Julian calendar, which drifted away from the Gregorian one by about a day per century, reaching 13 days by the twentieth century. Britain switched in 1752 and Russia in 1918, so documents from before a country's switch carry Julian dates and weekdays.
It is the signed count of calendar days between your chosen date and the current date: positive numbers point into the future, negative into the past, and zero means the chosen date is today.
ISO 8601 numbers the days Monday 1 through Sunday 7. It is handy for spreadsheets and data work, where the Sunday-first versus Monday-first ambiguity causes off-by-one mistakes.
The list filters a curated set of famous moments down to the ones that landed on the same weekday as your chosen date, showing up to ten matches sorted by year.