How to Find the Day of the Week for Any Date
Most people know their birthday, but far fewer know the weekday they were born on. The calendar repeats in a predictable pattern, so the day of the week for any date can be calculated exactly. This tool uses the Gregorian calendar, which most of the world uses today, and also shows your birthstone, the day of the year you were born, and which weekday your upcoming birthdays will fall on — handy for planning a party on a weekend.
Why your birthday moves one weekday each year
A common year has 365 days, which is 52 weeks plus 1 day. That extra day pushes your birthday forward by one weekday each year. After a February 29, the shift is two days. As a result, the calendar for a given year repeats only every 6, 11 or 28 years, depending on where the leap years fall.
Doing it in your head: the Doomsday rule
The mathematician John Conway devised the "Doomsday" method for calculating weekdays mentally. Certain easy-to-remember dates — 4/4, 6/6, 8/8, 10/10, 12/12, 5/9, 9/5, 7/11, 11/7 and the last day of February — always fall on the same weekday within any given year. For example, in 2026 that weekday is Saturday, so if you know a date is close to one of these anchor dates, you can count forwards or backwards to find its weekday.
Birthstones by month
| Month | Birthstone | Month | Birthstone |
|---|---|---|---|
| January | Garnet | July | Ruby |
| February | Amethyst | August | Peridot |
| March | Aquamarine | September | Sapphire |
| April | Diamond | October | Opal |
| May | Emerald | November | Topaz |
| June | Pearl | December | Turquoise |
The modern list above is based on the one adopted by the American National Retail Jewelers Association in 1912 and updated since. Several months have alternatives — for example alexandrite or moonstone for June, citrine for November, and tanzanite or zircon for December.
"Monday's Child"
The fortune-telling rhyme that begins "Monday's child is fair of face" was first recorded in England in the 19th century and is still widely quoted at baby showers and birthdays. It is pure folklore, of course — but it is a fun way to share the weekday you were born.
Notes on historical dates
Many countries switched from the Julian to the Gregorian calendar between 1582 and the early 20th century, skipping up to 13 days in the process. This calculator uses the Gregorian calendar for all dates (the so-called proleptic Gregorian calendar), so weekdays for very old dates may differ from those recorded at the time in countries that still used the Julian calendar.
Explore more about your birth date with the zodiac sign calculator and the generation calculator.
Frequently Asked Questions
What day of the week was I born?
Enter your date of birth above and the calculator shows the weekday instantly, along with your birthstone and the weekday of your next ten birthdays.
Which weekday are most babies born on?
In many countries, fewer births happen on weekends, partly because scheduled caesarean sections and inductions are usually planned for weekdays.
What if I was born on February 29?
In non-leap years, the calculator shows your birthday on February 28. Some people celebrate on March 1 instead — legally, the date used varies by country.
Does it work for historical dates?
Yes, using the Gregorian calendar for all dates. For dates before a country adopted the Gregorian calendar, the weekday may differ from historical records.
Disclaimer: Calculations use the Gregorian calendar and your device's local time zone. Results are provided as-is for informational purposes.
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