A birthday is more than a day on the calendar
Some dates come up often in birth records. Others stand out. This free birthday rarity calculator compares your month and day with all 366 possible dates, using 62,187,024 U.S. birth records from 2000–2014. Choose a date to see its rank, its approximate “1 in” frequency and how it compares with other calendar dates. You do not need to enter a birth year.
The result is a historical comparison, not a count of everyone alive with your birthday. The methodology explains the population, the calculation and why the leap-day result needs special care. We keep that context on the downloadable card too.
Find your date, then explore its neighbors
The calendar above links to a complete table for each month. Looking for May 14? Go straight to May 14 in the May rankings. A New Year birthday is in the January 1 row; a leap birthday has its own row in February. Every row includes its national rank and average births each time the date occurred.
For a wider comparison, explore the 30 rarest birthdays and the 30 most common birthdays. These use the same source and formula as the calculator, so the answers agree.
Put a few of your facts on one card
Your birthday is the beginning. Find how rare your first name was in a birth year, or look up your surname in the U.S. Census. The card maker combines the results into one image while keeping each comparison group visible. Names, surnames and birthdays are not independent measurements of personal uniqueness, so their probabilities are never multiplied together.
Save a portrait story or landscape image, or open a birthday share link with a preview of that date’s result. No account, upload or payment is needed. Personal names are looked up in your browser; see privacy for website delivery and analytics details.
Good questions
What is the rarest birthday?
February 29 has the fewest births across this 2000–2014 U.S. dataset because it occurs only four times. Among dates that occur every year, December 25 has the fewest recorded births.
What is the most common birthday?
September 12 ranks first in this SSA 2000–2014 sample. Other sources and periods can give a different answer, so a ranking needs a source and date range.
Can I use the card as a birthday filter?
You can save a portrait PNG and add it to a story, video or message. This site makes image cards; it is not an official TikTok or Instagram camera filter.