January birthdays ranked: January 1 is the rarest

Which January birthdays are rarest and most common?

January 1 is the rarest January birthday in these historical U.S. records, with 164,362 births. January 24 is the most common, with 233,021. The records cover 1994 through 2014.

January's most common date ranks 200 out of all 366 birthday dates. January 1 ranks 364. In both rankings, #1 means most common.

How much separates January's top dates?

January 24 leads January 10 by just 500 births across the whole period, or 0.22% relative to January 10. That is a small gap between the two highest totals.

Every January date occurs 21 times in this dataset. Dividing each total by 21 gives births per occurrence and leaves the order unchanged. February 29 works differently because it occurs less often; the full rare-birthday ranking explains that distinction.

Is January 8 a rare birthday?

January 8 is 27 in January's commonness ranking and 343 across the full year. It falls toward the less common end of both lists, but the ranking describes this historical sample. It does not count everyone alive today with a January 8 birthday.

Use the date comparison above to see how it differs from another January date, or check a birthday in any month.

Why is January 1 lower?

January 1 has fewer recorded births than any other January date. The records don't identify delivery methods or explain why births occurred when they did. The holiday birth study examines holiday dates against nearby days that fall on the same weekday, using one consistent source series. It provides a closer comparison than a rank alone.

The January 1 study compares New Year's Day with nearby dates. The January 2 study separates observed-holiday years from other years. The December 31 study covers New Year's Eve. Each study counts births on the recorded date, even when holiday observance moves.

Sources and what the ranking measures

These results use U.S. birth records compiled by FiveThirtyEight: CDC/NCHS for 1994 through 1999 and SSA for 2000 through 2014. January contributes 6,979,322 recorded births.

January rank compares the 31 dates in this month; overall rank compares all 366 month/day combinations. Birth share divides a date's count by all births in the selected 1994 through 2014 records, including births outside January. These are historical U.S. counts, not worldwide or current-population estimates.

See the methodology for source differences and calculations. To compare January as a whole with other months, use the birth-month guide, which accounts for month length.