How to use the what day of the week was i born
- Type your birth date into the field using the
YYYY-MM-DDformat, such as1990-06-15. - The result updates instantly to show the exact day of the week you were born.
- Read your traditional weekday rhyme from the Monday's child poem.
- Check the table below to see which day of the week your birthday falls on for the next five years.
How the weekday is calculated
To answer the question "what day of the week was I born", this tool reads the input as a year, month and day, builds that calendar date at midnight UTC with Date.UTC, and asks the calendar for its weekday. Using UTC keeps daylight saving time from shifting the date, and the answer follows the proleptic Gregorian calendar, which applies today's leap year rules backward in time.
The same answer can be worked out by hand with a formula such as Zeller's congruence, a classic method that treats January and February as months 13 and 14 of the previous year and reduces the result modulo 7. This tool does not run that formula, but it agrees with it: for 1990-06-15 both give Friday.
Monday's child nursery rhyme
The tradition of associating character traits with the day of the week you were born dates back to at least the 1830s in English folklore. Each weekday carries a specific line from the poem:
- 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.
- The child that is born on the Sabbath day (Sunday) is bonny and blithe, and good and gay.
When you look up what day you were born, the calculator matches your weekday to the correct verse automatically.
Day of the year explained
The day of the year is a number from 1 to 365 (or 366 in a leap year) representing how many days have elapsed since January 1. January 1 is always day 1. December 31 is day 365 in a common year and day 366 in a leap year.
This number is useful for scientific data logging, project management, and calculating precise intervals without worrying about varying month lengths. If you need to track the week number instead, that follows ISO 8601 rules where weeks start on Monday.
Why upcoming birthdays shift weekdays
A standard year has 365 days, which is exactly 52 weeks plus one extra day. Because of this remainder, your birthday advances by one weekday each common year. When a leap day falls between two consecutive birthdays, it advances by two weekdays instead: for a birthday from March to December that is the step into a leap year, and for a January or February birthday it is the step out of one.
For someone born on a Friday like June 15, 1990, their birthday in 1991 (a common year) falls on Saturday. By tracking these shifts over five years, you can easily plan celebrations or travel around weekends.
Common date entry mistakes
The most frequent error when finding out what day you were born is entering an invalid calendar date. February 29 only exists in leap years, which are divisible by 4, except for years divisible by 100 unless they are also divisible by 400. Therefore, 1900-02-29 is invalid, but 2000-02-29 is perfectly fine.
Another common issue is mixing up month and day order. This tool strictly requires the ISO 8601 format (YYYY-MM-DD) to eliminate ambiguity between American and European date conventions. Always use four digits for the year, two for the month, and two for the day.
Worked examples
| Example | Input | Result |
|---|---|---|
| Mid-June 1990 | Birth date: 1990-06-15 | Day of the week: Friday; Rhyme: Friday's child is loving and giving.; Day of the year: 166 |
| New Year's Day 2000 | Birth date: 2000-01-01 | Day of the week: Saturday; Rhyme: Saturday's child works hard for a living.; Day of the year: 1 |
| Leap day 2024 | Birth date: 2024-02-29 | Day of the week: Thursday; Rhyme: Thursday's child has far to go.; Day of the year: 60 |
| End of 2026 | Birth date: 2026-12-31 | Day of the week: Thursday; Rhyme: Thursday's child has far to go.; Day of the year: 365 |
FAQ
What format should I use for my birth date?
Use the YYYY-MM-DD format. For example, type 1990-06-15 for June 15, 1990. This prevents confusion between different regional date formats.
Can I check the day of the week I was born if I was born on February 29?
Yes. Enter your leap day birth date normally. For upcoming birthdays, the calculator shows February 28 for non-leap years, which is a common convention for leaplings (some places, such as the UK and New Zealand, treat March 1 as the legal date instead).
Is my personal data safe when I use this tool?
Yes. The calculation runs entirely in your browser using JavaScript. Your birth date is never sent to any server or saved anywhere.
Why does my birthday fall on a different day of the week each year?
A normal year has 365 days, which is 52 weeks plus one day. That extra day pushes your birthday forward by one weekday each year, or two weekdays after a leap year.
What does the Monday's child rhyme mean?
It is a traditional English nursery rhyme that assigns personality traits or fortunes to children based on the day of the week they were born. It has been popular since the 19th century.
Does this work for historical dates before 1900?
Yes, for any valid date from year 1 onward. The calculator uses the proleptic Gregorian calendar, meaning it applies modern calendar rules backward in time. Dates before a country adopted the Gregorian calendar (1582 in much of Europe, 1752 in Britain and its colonies) may show a different weekday from the one recorded at the time under the Julian calendar.