Have you ever wondered, how rare is my birthday compared with everyone else’s? Enter your date of birth in the birthday rarity calculator below to see where your birthday ranks among all 366 possible calendar dates.
How Rare Is My Birthday?
Enter your date of birth to discover where it ranks among 366 calendar dates, using U.S. birth frequency data from 1994–2014.
Enter Your Full Birthday
Enter your month, day, and birth year to see your result
On this calendar date, based on U.S. birth data.
Compared with the average calendar day.
of all birthdays on the calendar.
of all birthdays on the calendar.
Ranking based on U.S. birth data from 1994–2014, using CDC NCHS / SSA data compiled by FiveThirtyEight. Every calendar date is ranked from most common to rarest. Results are for informational purposes.
The birthday rarity ranking is based on your month and day, while your birth year is used for the additional calculations. If you want to explore your complete date of birth, you can also use our Date of Birth Calculator.
How Does the Birthday Rarity Calculator Work?
The birthday rarity checker compares your month and day with birth-frequency data for the 366 calendar dates. Each date receives a ranking based on how frequently births occurred on that date.
The ranking runs from #1 to #366:
- #1 represents the most common birthday in the dataset.
- #366 represents the least common birthday.
- A lower number means the date occurs more frequently.
- A higher number means the date is less common.
For example, September 9 ranks at the very common end of the dataset, while December 25 ranks at the rarest end. February 29 is also unusual because it only appears on the calendar during leap years.
When you enter your birthday, the calculator looks up your calendar date and displays its corresponding ranking.
The year you enter is used for the additional age, countdown, and life-stat calculations, while the birthday rarity ranking itself is based on the month and day.
What Does “How Rare Is My Birthday” Actually Mean?
When people ask how rare is my birthday, they are usually asking how frequently people are born on their particular calendar date compared with other dates.
Birthday rarity is therefore different from asking how many people were born in a particular year.
For example, two people born on September 9 in different years have the same calendar birthday for the purposes of this ranking. Their individual birth years do not change the underlying frequency of September 9.
The important factor is the month and day.
This is why a birthday rarity ranking can tell you whether your date is relatively common or unusual without needing to know the total number of people currently alive who share it.
How Rare Is Your Birthday Compared With Other Dates?
If you are wondering how rare is your birthday, the most useful comparison is against the other dates on the calendar.
Some birthdays consistently appear toward the more common end of the ranking, while others are affected by holidays, seasonal patterns, weekends, scheduling practices, and other factors that influence when births occur.
The difference can be surprisingly large.
The calculator therefore provides more than a simple “rare” or “common” label. Your result includes a numerical ranking out of 366, allowing you to see exactly where your date falls.
For example:
#1 of 366 means your date is the most common in the ranking.
#183 of 366 would place your date approximately around the middle.
#366 of 366 means your date is the rarest in the ranking.
This makes it easier to compare your birthday directly with someone else’s.
Your birthday is more than just a date on the calendar. If you're interested in another birthday-related calculation, you can also find out when your half birthday falls with our Half Birthday Calculator.
What Is the Rarest Birthday?
Based on the U.S. birth-frequency dataset used by this calculator, December 25 ranks #366, making Christmas Day the least common calendar date in the ranking.
This does not necessarily mean that December 25 is the rarest birthday in every country or in every historical period. Birth patterns vary by location, time period, medical practices, holidays, and other demographic factors.
That distinction matters when interpreting birthday statistics.
The calculator is specifically designed around the U.S. birth-frequency data used for its ranking rather than claiming that the same order applies worldwide.
What Is the Most Common Birthday?
In the dataset used by this birthday rarity checker, September 9 ranks #1, placing it at the most common end of the 366-date ranking.
Several dates around September also appear relatively high in the ranking. Birth frequencies are not evenly distributed throughout the year, so certain periods can contain noticeably more birthdays than others.
This is one reason simply dividing the population by 365 does not give an accurate picture of birthday frequency.
Why Are Some Birthdays More Common Than Others?
It might seem logical that every day should have roughly the same number of births, but real-world birth data does not work that way.
Birth frequency can be affected by several factors, including:
Scheduled births
Induced labor and planned cesarean deliveries can influence when babies are born. Unlike spontaneous labor, these births can be scheduled around medical and practical considerations.
Holidays
Births around major holidays can show unusual patterns. December 25 is a particularly notable example in the dataset because it has substantially fewer births than many ordinary calendar dates.
Weekends
Birth patterns can differ between weekdays and weekends. Some scheduled procedures are less likely to take place on weekends, which can influence the number of recorded births.
Seasonal patterns
Birth frequency can also vary throughout the year. These differences may reflect conception patterns, holidays, cultural behavior, and other population-level factors.
Because of these influences, your birthday is not equally likely as every other day of the year.
How Does the Birthday Rarity Checker Rank My Date?
The birthday rarity checker uses the calendar date you enter and matches it with the corresponding ranking in its dataset.
Your result includes several useful measurements.
Calendar Rank
This is your primary birthday rarity score, displayed out of 366.
The calculator treats #1 as the most common and #366 as the rarest.
Average Births Per Day
The result also shows the average number of births associated with your calendar date in the underlying U.S. dataset.
This gives you a more concrete idea of how frequently your date appeared in the source data.
Compared With the Average Day
Your result shows whether your birthday had more or fewer births than the average calendar day in the dataset.
This provides another way to understand the difference between your date and a typical calendar date.
More Common Than
This percentage indicates how many calendar dates are less common than your birthday.
Rarer Than
This provides the complementary view, showing how your birthday compares with the full set of calendar dates.
Together, these statistics give you a more detailed answer than simply labeling your birthday “rare.”
What About February 29?
February 29 is a special case because it only occurs during leap years.
The calculator includes February 29 in its full 366-date ranking. This is important because a conventional 365-day birthday list would leave out one calendar date entirely.
If you were born on February 29, the calculator identifies you as a Leap Day baby and displays your ranking separately from the standard 365-day dates.
Leap Day birthdays are unusual for a simple calendar reason: February 29 does not occur every year.
How Rare Is My Birthday Compared With My Friends?
One of the easiest ways to use the calculator is to compare birthdays.
Ask each person to enter their own date and record their ranking. You can then compare the numbers.
Remember that a higher rank number means a rarer birthday in this calculator.
For example:
- Person A: #18
- Person B: #142
- Person C: #287
- Person D: #361
Person D has the rarest birthday among these four dates because #361 is closest to #366.
This can make the birthday rarity calculator a fun activity for birthday parties, family conversations, classrooms, or social media.
Does My Birth Year Affect My Birthday Rarity?
No. Your calendar birthday ranking is based on your month and day, not the year you were born.
However, the calculator does use your birth year for other features on the results page, including your current age, total months and days lived, birthday countdown, estimated heartbeats, estimated breaths, and Life Path calculation.
This means the tool combines your calendar birthday rarity with several additional birthday-related calculations.
How Accurate Is the Birthday Rarity Calculator?
The calculator uses a defined U.S. birth-frequency dataset covering births from 1994 through 2014. The underlying source is CDC NCHS / SSA data compiled through FiveThirtyEight.
Because the ranking is based on a specific dataset and time period, it should not be interpreted as a universal ranking for every country or every generation.
Birth patterns can change over time, and different countries can have different distributions.
For that reason, the result is best viewed as a data-based comparison of U.S. birthday frequency during the period represented by the dataset.
Birthday Rarity Categories
Your result is also assigned a category based on its position in the 366-date ranking.
The calculator currently uses these ranges:
| Rank | Category |
|---|---|
| #1–73 | Very Common |
| #74–146 | Common |
| #147–219 | Average |
| #220–293 | Uncommon |
| #294–346 | Rare |
| #347–366 | Extremely Rare |
These categories provide a quick way to understand your result without having to interpret the ranking number alone.
A birthday ranked #350, for example, is not merely somewhat uncommon. It falls within the calculator’s Extremely Rare range.
How to Find Out How Rare Your Birthday Is
Finding your birthday ranking takes only a few seconds.
1. Enter your birth month.
Select the month in which you were born.
2. Select your birth day.
Choose the correct calendar date.
3. Enter your birth year.
The year is required for the additional calculations shown in your results.
4. Select “Check My Birthday Rarity.”
Your birthday rarity result will appear immediately.
You will then see your calendar ranking, rarity category, birth-frequency statistics, zodiac sign, birthday personality profile, countdown information, and additional life statistics.
Frequently Asked Questions
How rare is my birthday?
What is the birthday rarity calculator based on?
The calculator uses U.S. birth-frequency data covering 1994–2014, based on CDC NCHS / SSA data compiled by FiveThirtyEight.
What is the rarest birthday?
What is the most common birthday?
September 9 ranks #1 in the dataset used by the calculator.
Is February 29 the rarest birthday?
Not according to this ranking. February 29 is unusual because it only occurs during leap years, but its frequency ranking in this dataset is different from its calendar rarity.
Does my birth year change my birthday rarity rank?
No. The rarity ranking is determined by your month and day. Your birth year is used for other calculations displayed in the results.
Is birthday rarity the same worldwide?
No. Birth frequency varies by country, population, time period, medical practices, holidays, and other factors. This calculator specifically uses U.S. data from 1994–2014.
Find Out How Rare Your Birthday Is
Your birthday is one of the few dates that will always be uniquely yours, but the date itself may be much more common or unusual than you expect.
Use the calculator above to find your ranking among all 366 calendar dates and see whether your birthday is very common, common, average, uncommon, rare, or extremely rare.
And once you know your result, compare it with your friends and family. You may be surprised by whose birthday ends up closest to #366.
