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Day of the Week Born
Works for any date from 1800 to today
Monday
You were born on a Monday
Facts About Your Birth Day
What Day of the Week Were You Born?
Enter any birth date and the calculator shows the weekday, your age in days and the weekday of your next birthday. For example, June 15, 1990 was a Friday. In US birth records Tuesday is the most common day to be born and Sunday the least common, because scheduled inductions and C-sections happen mostly on weekdays.
Births by Day of the Week
US births in 2000, from the National Center for Health Statistics. The index compares each weekday with the average day (100).
| Day | Average births per day | Index | Share of births |
|---|---|---|---|
| Sunday | 8,052 | 72.6 | 10.4% |
| Monday | 11,355 | 102.4 | 14.6% |
| Tuesday | 12,581 | 113.4 | 16.2% |
| Wednesday | 12,463 | 112.4 | 16.0% |
| Thursday | 12,430 | 112.1 | 16.0% |
| Friday | 12,042 | 108.6 | 15.5% |
| Saturday | 8,807 | 79.4 | 11.3% |
Sunday had about 36% fewer births than Tuesday. The weekend gap is much larger for planned cesarean deliveries than for vaginal births, which shows how much hospital scheduling shapes the pattern.
Find the Weekday by Hand
Zeller's congruence works for any Gregorian date. Treat January and February as months 13 and 14 of the previous year, then:
h = (q + ⌊13(m + 1) ÷ 5⌋ + K + ⌊K ÷ 4⌋ + ⌊J ÷ 4⌋ + 5J) mod 7
q is the day of the month, m the month, K the last two digits of the year and J the first two. The answer h runs 0 = Saturday, 1 = Sunday, through 6 = Friday.
Worked example: June 15, 1990
q = 15, m = 6, K = 90, J = 19. Then 15 + 18 + 90 + 22 + 4 + 95 = 244, and 244 mod 7 = 6, so it was a Friday.
Why Your Birthday Moves Each Year
A 365-day year is 52 weeks plus 1 day, so your birthday usually falls one weekday later each year: Friday, then Saturday, then Sunday. When a February 29 falls in between, it jumps two days. Between 1901 and 2099 the whole calendar repeats every 28 years, so the weekday of your 28th birthday matches the day you were born.
Method and sources. Weekdays are calculated with the proleptic Gregorian calendar from the date you enter, in your local time zone. Every famous birthday on this page was checked by computing its weekday. Births by day of week: National Center for Health Statistics, Births: Final Data for 2000 (National Vital Statistics Reports, vol. 50, no. 5). Leap year rule: divisible by 4, except century years not divisible by 400.
Birth Day Questions
This calculator uses JavaScript's built-in Date object, which implements the Gregorian calendar proleptic extension back to before the calendar's adoption in 1582. For any date from 1800 onwards, the result is accurate. The calculation converts your birthday to a day-of-week index (0 = Sunday through 6 = Saturday) using the Date.getDay() method, which counts days from the Unix epoch (January 1, 1970). The algorithm correctly handles leap years, century years (which are not leap years unless divisible by 400), and all calendar irregularities.
Monday comes from the Old English "Monandaeg", the Moon's day (Latin dies Lunae). The old nursery rhyme says "Monday's child is fair of face", which is folklore rather than fact. Leonardo DiCaprio, Tom Hanks, Elon Musk and Mark Twain were all born on a Monday. In US birth data Monday is an ordinary weekday: in 2000 it had about 2% more births than the average day, fewer than Tuesday through Friday but far more than the weekend.
In the United States it is Tuesday. In National Center for Health Statistics data for 2000, Tuesday averaged 12,581 births a day, followed closely by Wednesday (12,463) and Thursday (12,430). Sunday was the least common at 8,052, about 36% below Tuesday, and Saturday was next at 8,807. The gap comes from scheduled inductions and cesarean deliveries, which hospitals mostly book on weekdays; for repeat cesareans the Sunday index was only 41, against 78 for vaginal births.
The traditional English nursery rhyme "Monday's Child" dates to the 19th century and assigns a personality trait to each day: Monday's child is fair of face. Tuesday's child is full of grace. Wednesday's child is full of woe. Thursday's child has far to go. Friday's child is loving and giving. Saturday's child works hard for a living. And the child born on the Sabbath day is bonny and blithe and good and gay. This rhyme has no scientific basis: it's a piece of folk tradition. Variations exist in different cultures, some associating days of the week with the seven classical planets (Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn), which is how the days got their names.
The seven-day week and the names of the days come from a mix of Latin, Germanic, and Norse traditions. Sunday: from the Sun (Latin: dies Solis). Monday: from the Moon (Latin: dies Lunae). Tuesday: from Tiw, the Norse god of single combat (Latin: dies Martis, Mars). Wednesday: from Woden (Odin), the chief Norse god (Latin: dies Mercurii, Mercury). Thursday: from Thor, the Norse god of thunder (Latin: dies Jovis, Jupiter). Friday: from Frigg or Freya, Norse goddesses (Latin: dies Veneris, Venus). Saturday: the only day that kept its Latin name in English, from Saturn (dies Saturni). The seven-day week originated in ancient Babylon, was adopted by the Romans, and spread throughout Europe via Christianity and Roman culture.
Each of these was checked by calculating the weekday of the birth date. Sunday: Abraham Lincoln, Michael Jordan, Zendaya. Monday: Leonardo DiCaprio, Tom Hanks, Elon Musk. Tuesday: Marilyn Monroe, Elvis Presley, Martin Luther King Jr., Cristiano Ronaldo. Wednesday: Taylor Swift, Lionel Messi, Meryl Streep. Thursday: Nelson Mandela, Walt Disney, Stephen Hawking, Steve Jobs. Friday: Barack Obama, Albert Einstein, Bill Gates, Beyonce. Saturday: J.K. Rowling, Muhammad Ali, Audrey Hepburn. For people born before their country adopted the Gregorian calendar (1752 in Britain and its colonies), make sure you use the New Style date: converting between calendars changes the date but not the weekday.
Yes, this calculator works for any date from 1800 onwards. For historical context: D-Day (June 6, 1944) was a Tuesday. The moon landing (July 20, 1969) was a Sunday. The September 11 attacks (2001) were on a Tuesday. The fall of the Berlin Wall began on a Thursday (November 9, 1989). Christmas Day 2000 was a Monday. For dates before 1752 in Britain or before Gregorian calendar adoption in other countries, there is ambiguity because historians use two different conventions (Old Style Julian calendar vs New Style Gregorian calendar). Our calculator uses the proleptic Gregorian calendar for all dates, which is the modern historical convention.
A leap year adds an extra day (February 29) to keep the calendar aligned with Earth's 365.25-day orbit around the Sun. Leap year rules: a year is a leap year if divisible by 4, unless it is divisible by 100, in which case it is NOT a leap year, unless it is also divisible by 400, in which case it IS a leap year. So 1900 was not a leap year (divisible by 100 but not 400) but 2000 was (divisible by 400). People born on February 29 (Leaplings) technically only have a birthday every 4 years. They typically celebrate on February 28 or March 1 in non-leap years. This calculator correctly handles February 29 birthdays. The next leap year after 2024 is 2028.
In traditional Western astrology and various folk traditions, each day of the week is ruled by a celestial body: Sunday by the Sun, Monday by the Moon, Tuesday by Mars, Wednesday by Mercury, Thursday by Jupiter, Friday by Venus, Saturday by Saturn. These planetary associations carry attributed characteristics: for example, people born on Thursdays (Jupiter's day) are said to be generous, philosophical, and lucky. In Vedic astrology (Jyotish), the day of the week at birth (vara) is one of several factors considered alongside the moon sign, rising sign, and planetary positions. Different cultures have different interpretations, from the nine-planet system in Hindu astrology to the Ba Zi (Four Pillars) system in Chinese astrology which does not use weekdays at all.
The number of days you have been alive is calculated as the difference between today's date and your birth date, counting every calendar day including leap days. The result shown in this calculator updates in real time based on the current date. At 30 years old, you have lived approximately 10,957 days (accounting for leap years). At 50 years old, approximately 18,263 days. At 100 years old, approximately 36,524 days. The exact number depends on how many leap years fell in your lifetime: about one extra day for every 4 years. February 29 babies who count their "actual" birthdays have lived through fewer of their specific calendar date, but they have lived the same number of total days as anyone born on the same date.
Usually one weekday later than this year, because 365 days is 52 weeks and 1 day. If a February 29 falls between this birthday and the next, it moves two days instead. The calculator shows the weekday of your next birthday automatically.
Yes and no. England still used the Julian calendar in 1642, and by that calendar Newton was born on December 25, 1642. On the Gregorian calendar used today the same day is January 4, 1643. Either way it was a Sunday: switching calendars changes the date, not the weekday. Typing December 25, 1642 into a Gregorian calculator like this one gives Thursday, which is the classic mistake with Old Style dates.