What Day of the Week Was I Born? Find It in 30 Seconds

What day of the week was I born? You can find out in under a minute. The fastest way is to look up your birth date in a calendar app or spreadsheet. If you would rather work it out in your head, the doomsday rule lets you find the weekday of any date with simple arithmetic. This guide shows both, with worked examples you can check, plus the old “Monday’s child” rhyme people often look up next.

For other birthday numbers, such as your exact age in days or your next half birthday, try our age in days calculator and half birthday guide.

The quick way: look it up

Three tools give you the answer instantly:

• Phone calendar. Open your calendar app, jump to your birth month and year, and read the weekday at the top of the column. Most apps scroll back decades.
• Spreadsheet. In Google Sheets or Excel, type your birth date into cell A1, then enter =TEXT(A1,"dddd") in another cell. It returns the full weekday name, such as Wednesday.
• Search engine. Typing “what day of the week was March 14, 1990” usually returns the weekday directly.

These are reliable for any date after the Gregorian calendar was in use where you were born. In the United States and Britain, that means any date after September 1752, which covers everyone alive today.

The mental-math way: the doomsday rule

The doomsday rule was devised by the mathematician John Conway. It works because certain easy-to-remember dates always fall on the same weekday as each other in any given year. That shared weekday is called the year’s doomsday. Once you know it, you count from the nearest memorable date to your birthday.

Step 1: learn the memorable dates

In every year, these dates fall on the same weekday:

Month	Doomsday date	Memory trick
January	3rd (4th in leap years)	“3 years out of 4, the 3rd; the 4th in the 4th”
February	28th (29th in leap years)	last day of February
March	14th	Pi Day, 3/14
April	4th	4/4
May	9th	”9 to 5 at the 7-11”: 5/9
June	6th	6/6
July	11th	7/11
August	8th	8/8
September	5th	9/5
October	10th	10/10
November	7th	11/7
December	12th	12/12

The even months are doubles (4/4, 6/6, 8/8, 10/10, 12/12). The odd months from May on pair up as 5/9 and 9/5, 7/11 and 11/7. Those two phrases cover most of the year.

Step 2: know the century anchor

Each century has a starting weekday:

Century	Anchor day
1800s	Friday
1900s	Wednesday
2000s	Tuesday
2100s	Sunday

Step 3: find the year’s doomsday

Take the last two digits of the year and do four quick steps:

1. Divide by 12 and write down the whole number (call it a).
2. Write down the remainder (b).
3. Divide the remainder by 4 and write down the whole number (c).
4. Add a + b + c, then add that many days to the century anchor. If the total is 7 or more, take away 7s first.

Step 4: count to your birthday

Find the nearest doomsday date in your birth month and count forward or back. Weeks repeat every 7 days, so jumping by 7 keeps the same weekday.

Worked example 1: March 14, 1990

1. The year is 1990, so the anchor is Wednesday and the last two digits are 90.
2. 90 ÷ 12 = 7 with remainder 6. So a = 7, b = 6.
3. 6 ÷ 4 = 1 (whole number). So c = 1.
4. 7 + 6 + 1 = 14. Take away two 7s and you get 0. Wednesday + 0 = Wednesday.

March’s doomsday is the 14th, so March 14, 1990 was a Wednesday. You can confirm it on our born in 1990 page or in any calendar app.

Worked example 2: July 20, 1969

This is the date of the first Moon landing.

1. Anchor for the 1900s: Wednesday. Last two digits: 69.
2. 69 ÷ 12 = 5 remainder 9. So a = 5, b = 9.
3. 9 ÷ 4 = 2. So c = 2.
4. 5 + 9 + 2 = 16. Take away two 7s: 2. Wednesday + 2 = Friday.

July’s doomsday is 7/11, a Friday. Add 7 to reach July 18, also a Friday. July 20 is two days later: Sunday.

Worked example 3: February 29, 2012

1. Anchor for the 2000s: Tuesday. Last two digits: 12.
2. 12 ÷ 12 = 1 remainder 0. So a = 1, b = 0, c = 0.
3. 1 + 0 + 0 = 1. Tuesday + 1 = Wednesday.

2012 is a leap year, so February’s doomsday is the 29th. February 29, 2012 was a Wednesday. If you or someone you know has a leap-day birthday, our leap year age calculation guide explains how those birthdays are counted.

Why the doomsday rule works

The method relies on two facts. First, a normal year has 365 days, which is 52 weeks plus 1 day. So each new year shifts every date forward by one weekday, and a leap year shifts it by two. The “divide by 12” steps are a shortcut for adding up those shifts over the years since the start of the century: every 12 years contain exactly three leap years, and 12 + 3 = 15 days of shift, which is 1 week plus 1 day. That is why each group of 12 years adds one day.

Second, the memorable dates are spaced a whole number of weeks apart. April 4 to June 6 is 63 days, which is exactly 9 weeks. June 6 to August 8 is also 63 days. Because the gaps are multiples of 7, all those dates land on the same weekday. Conway chose dates that are easy to recall so the counting step is short.

Worked example 4: your 2027 birthday

You can use the same rule to look ahead. For any date in 2027:

1. Anchor for the 2000s: Tuesday. Last two digits: 27.
2. 27 ÷ 12 = 2 remainder 3. So a = 2, b = 3.
3. 3 ÷ 4 = 0. So c = 0.
4. 2 + 3 + 0 = 5. Tuesday + 5 = Sunday.

So every doomsday date in 2027 is a Sunday. If your birthday is August 10, start at August 8 (Sunday) and count two days: your 2027 birthday is a Tuesday.

Tips for getting it right

• Check for a leap year. Only January and February change in leap years. A year is a leap year if it divides by 4, except century years, which must divide by 400. So 2000 was a leap year and 1900 was not.
• Count in sevens. Moving 7, 14, 21 or 28 days keeps the same weekday. Jump in weeks, then count the last few days.
• Practise with known dates. Check your answer against a calendar for a few dates you already know, such as last Christmas or your own birthday.
• Use your fingers. Many people count the days forward from the anchor on their fingers while learning. Speed comes quickly.

With practice, most people can find a weekday in 20 to 30 seconds. It is a popular party trick and a great mental-math exercise for students.

The “Monday’s child” rhyme

Once people know their birth weekday, many look up the traditional nursery rhyme. It was first recorded in England in the 1830s, and versions vary slightly. The most common one goes:

Day	Line from the rhyme
Monday	Monday’s child is fair of face
Tuesday	Tuesday’s child is full of grace
Wednesday	Wednesday’s child is full of woe
Thursday	Thursday’s child has far to go
Friday	Friday’s child is loving and giving
Saturday	Saturday’s child works hard for a living
Sunday	The child born on the Sabbath day is bonny and blithe, good and gay

The rhyme is folklore for fun, not a prediction about anyone’s personality. It makes a nice addition to a birthday card or a baby book.

Are some weekdays more common for births?

In the United States, fewer births happen on weekends than on weekdays. The main reason is scheduling: planned cesarean deliveries and inductions are usually booked on weekdays. National birth data from the CDC has shown this pattern for decades. So if you were born on a Tuesday or Wednesday, you share your birth weekday with more people than someone born on a Sunday.

Fun ways to use your birth weekday

• Birthday planning. Your birthday moves forward one weekday each year, or two after February 29 in a leap year. Knowing this helps you plan a weekend party years ahead.
• Genealogy. Old records sometimes give a weekday but not a date. The doomsday rule can help check whether a record matches.
• Classroom math. Teachers use the method to practise division, remainders and modular thinking in a way students enjoy.
• Generation facts. Combine your birth weekday with your generation from our what generation am I guide for a fun profile.

Frequently Asked Questions