Day of the Week
Calculator
Find out what day of the week any date falls on
What day was/is…
How it works
Every date falls on one of seven weekdays in a repeating cycle. The Gregorian calendar advances by one weekday each year, but leap years shift the pattern by an extra day — so the same calendar date lands on a different weekday almost every year.
Clockr calculates the day of the week using JavaScript's built-in date library, which accounts for leap years and century-year exceptions back to 1582 when the Gregorian calendar was introduced. Enter any date and the result appears instantly — no lookup tables or mental arithmetic required.
The "Born on a…" chart counts how many times your month-and-day combination fell on each weekday over the past century. Because of the leap-year cycle, most dates land on each weekday between 14 and 15 times per 100 years — but February 29th is the rare exception, appearing on each weekday only about twice per century.
Frequently asked questions
What day of the week was I born?
Enter your date of birth into the calculator above. The tool instantly shows the weekday — Monday, Tuesday, and so on — along with whether that date is in the past, present, or future relative to today. The "Born on a…" section also reveals how often your birthday has fallen on each weekday over the last 100 years.
How do I find out what day a date falls on?
Type or pick any date using the date input at the top of this page. As soon as you enter a valid date, Clockr displays the weekday in large text along with the week number of the year. You can also click one of the quick-reference buttons — Today, Tomorrow, Yesterday, or a preset historical date — for an instant answer.
What day of the week is Christmas 2026?
Christmas Day 2026 falls on a Friday. Click the "25 December 2026" button in the quick-reference section above to see the result instantly, or enter 2026-12-25 in the date field.
How many times does a date fall on the same weekday in 100 years?
Most calendar dates (like 15 March or 4 July) fall on each weekday between 14 and 15 times over any 100-year span, because the 400-year Gregorian cycle distributes weekdays almost evenly. The "Born on a…" bar chart on this page shows the exact distribution for your chosen date. February 29th is the outlier — it occurs only about 24 times per century and lands on each weekday roughly twice.
What is the Doomsday algorithm?
The Doomsday algorithm is a mental-math technique invented by John Horton Conway for calculating weekdays without a calendar. It works by memorising a few "doomsday" anchor dates that always fall on the same weekday in a given year — such as 4 April, 6 June, and 31 December — then counting forward or backward from the nearest anchor. With practice you can determine any date's weekday in seconds, but a calculator is faster for most people.
Why does the same date fall on different days each year?
A common year has 365 days, which is 52 weeks plus one extra day. That means every date shifts forward by one weekday the following year. Leap years add a second shift, so dates after February 29 jump two weekdays instead of one. Over four years the shifts cancel out for most dates, but the century-year rules create a longer 400-year cycle before the pattern fully repeats.
What day of the week occurs most often on the 13th?
Friday is the most common weekday for the 13th of any month. In the 400-year Gregorian cycle, the 13th falls on a Friday 688 times compared with 685 times for Thursday and Saturday and 684 for the other weekdays. This slight imbalance is what fuels the superstition around Friday the 13th — it genuinely occurs more often than any other weekday–date combination.
How do I calculate the day of the week for any date in history?
For dates after 15 October 1582 (when the Gregorian calendar was adopted in much of Europe), enter the date directly into this calculator. For earlier dates you need to account for the Julian calendar and regional adoption dates — Britain, for example, did not switch until 1752. Historical researchers often use specialised tools or the Zeller's congruence formula for pre-Gregorian dates.