Rarest Birthdays in the U.S.: The Least Common Dates Explained

How rare is your birthday?

Pick a month and day in the birthday rarity checker. It shows your date’s position among all 366 calendar dates, the average number of recorded U.S. births, and how the result changes when leap day is counted across all years. The lookup uses historical data; it does not ask for your birth year or predict today’s birth rate.

Want a date picked for a character or game? Try the Random Birthday Generator, then return here to check how common that date was in the U.S. records.

The 10 least common birthdays that occur every year

These are the ten dates with the lowest average births per occurrence in our U.S. analysis. We excluded February 29 from this particular table because it appears only in leap years; it is examined separately below. Rank #366 means rarest of all 366 dates under the per-occurrence method.

Rounded averages for 1994–2014; our calculation from FiveThirtyEight’s CDC/NCHS and SSA daily birth files. A “rank of 366” compares all dates, including February 29 after adjustment for its five occurrences.

Christmas Day heads the recurring-date list. New Year’s Day, Christmas Eve, Independence Day, and Halloween also appear. The late-November dates partly reflect the U.S. Thanksgiving period, but Thanksgiving itself moves between dates, so a single November date is not a fixed holiday every year.

How were the rarest birthdays ranked?

We combined two published daily U.S. birth files: CDC/NCHS data for 1994–1999 and SSA data for 2000–2014. The source files overlap in 2000–2003, so we included those years only once. The resulting 21-year period contains 85,712,738 recorded births across 7,670 calendar days.

Our checker lets you switch between both methods. Importantly, we have not combined overlapping years or treated February 29 as if it happened annually. The source data is shared by FiveThirtyEight under CC BY 4.0; the aggregation and two ranking modes are our calculations.

Is February 29 the rarest birthday?

Yes, when you count births across calendar years. February 29 appeared only five times between 1994 and 2014. The records contain 52,561 leap-day births in those five occurrences, or about 2,503 per year averaged over the entire 21-year period. On that basis, it ranks #366, the rarest.

No, when you compare each date only on days it occurs. An average of about 10,512 babies were born on February 29 itself, placing it #347 out of 366 in our per-occurrence ranking. December 25, at about 6,601 births each time it occurred, is lower. Both answers are valid, but they measure different things.

Why are Christmas and other holidays rare birthdays?

People give birth on holidays, of course. However, elective deliveries can be moved to other dates. That changes the number of births recorded on a particular day without changing the number of pregnancies that existed. A study in the Journal of Labor Economics found fewer births on and immediately after major holidays in California, with cesarean scheduling explaining part of the difference.

The pattern does not mean every rare date is caused by scheduling. Weekdays, changing holiday dates, seasonal patterns, and the length of the dataset also matter. The UK Office for National Statistics observed a holiday dip in England and Wales as well, but its date rankings are not interchangeable with U.S. rankings.

What is the rarest month to be born in?

It depends on whether you mean total births or average births per calendar day. February had the fewest total births in this 1994–2014 U.S. dataset: 6,511,697. Yet February is the shortest month, so its low total does not mean each February date is unusually rare. January had the lowest average daily birth count, about 10,721 in our calculation.

The same distinction changes the “most common month” answer. August had the most births in total, while September had the highest average per calendar day. In fact, September 9 was the single most common date in these records, at roughly 12,344 births per occurrence.

These month comparisons are our calculations from the same 1994–2014 U.S. source files; they are not a claim about the most recent birth year or every country.

Three mistakes to avoid when reading birthday rankings

1. Calling a U.S. list a world ranking. Countries have different holidays, birth patterns, and available records. Our table is U.S.-specific.
2. Mixing up the rarest month and the rarest date. A month’s length affects its total; a holiday affects an individual date.
3. Ignoring the time period. These are historical 1994–2014 averages, not live figures for 2026. CDC’s birth-data portal provides newer national birth totals, but those totals do not update the ranking here.