How common is your birthday?

Analysis of births* data from 1980 to 2015 shows:

• 30 September is the most common birthday
• the 10 most common birthdays all appear in the 10-day period from 22 September to 1 October
• the least common birthday is 25 December (apart from 29 February, which only occurs in leap years)
• the least common birthdays tend to be around public holidays: 24–27 December, 1–2 January, 6 February (Waitangi Day), 25 April (ANZAC Day).

A similar pattern occurs in Australia, England and Wales, and the United States.  

Most common birthday table

Days are ranked 1 to 366 by number of births, where 1 is the most common birthday and 366 is the least common birthday. Some days are tied for ranking because they have had the same number of births (eg 7 and 15 October).

Shading is based on rank. Darker shading indicates more common birthdays, lighter shading indicates less common birthdays.

Click the image below to view a larger version of the table.

_{* Live births to mothers resident in New Zealand, registered in New Zealand during 1980–2015.}

Updated 02 March 2016