How Rare Is Your Birthday?

Birthday Frequency Demographics

Birth rates spike in September due to winter holiday conceptions, while major holidays like Christmas and New Year's Day see the fewest births. In the Northern Hemisphere, late summer and early fall consistently produce the most birthdays, while January and February tend to be quieter. The pattern is remarkably consistent year after year across multiple countries.

Rankings Across 365 Days

September 9th is statistically the most common birthday in the US, while December 25th is the rarest. Other rare birthdays include January 1st, July 4th (in the US), and February 29th (leap day — which only comes around once every four years). If your birthday lands on a rare date, you are part of a much smaller club than you might think.

The Science Behind the Patterns

These patterns are not random — they are driven by seasonal factors like holidays, weather, and even vitamin D levels affecting conception rates. The Christmas holiday season, Thanksgiving, and New Year's Eve all contribute to the September baby boom. Induced births and scheduled C-sections also skew weekdays to be more common than weekend births.

What Your Birthday Rank Means

Having a rare birthday is a fun conversation piece and can make you feel special, but it also means sharing your birthday with fewer people — which for some is a point of pride. A common birthday means more company and often more collective celebrations. Either way, your birthday's rarity is just one interesting data point about who you are.