๐ Rarest Birthdays: All 366 Days Ranked (2026 Data)
Quick Answer: Rarest and Most Common Birthdays
The rarest birthday is February 29 (Leap Day), which only exists every four years. Among regular dates, December 25 is the rarest, followed by January 1 and December 24. The most common birthday is September 9, followed by September 19 and September 12; nine of the ten most common dates fall in September. Figures are average annual US births, as used throughout this page.
| # | Rarest date | Avg births | Most common date | Avg births |
|---|---|---|---|---|
| 1 | Feb 29 | ~1,000* | Sep 9 | 12,301 |
| 2 | Dec 25 | 6,574 | Sep 19 | 12,229 |
| 3 | Jan 1 | 7,792 | Sep 12 | 12,209 |
| 4 | Dec 24 | 8,069 | Sep 17 | 12,148 |
| 5 | Jul 4 | 8,796 | Sep 10 | 12,143 |
| 6 | Jan 2 | 9,307 | Jul 7 | 12,113 |
| 7 | Dec 26 | 9,543 | Sep 20 | 12,100 |
| 8 | Nov 27 | 9,718 | Sep 15 | 12,082 |
| 9 | Nov 23 | 9,883 | Sep 16 | 12,064 |
| 10 | Oct 31 | 9,978 | Sep 18 | 12,055 |
* The February 29 figure is averaged over all years, including non-leap years, as in the full table below. See the 20 rarest birthdays for the next ten dates, or check where your own birthday ranks.
Why Some Birthdays Are Rarer
The distribution of birthdays across the year is not random. Three key factors create predictable patterns: scheduled C-sections and inductions (about 1 in 3 US births) are rarely scheduled on holidays or weekends, the holiday season in November-December drives higher conception rates creating the September birth peak, and cultural factors like avoiding births on dates perceived as unlucky (April 1, September 11 post-2001) create additional dips.
The 20 Rarest Birthdays (US Data)
Ranked by average annual births. Data from CDC/FiveThirtyEight analysis of US births 1994โ2014.
| # | Date | Avg Births | Reason |
|---|---|---|---|
| 1 | February 29 | ~1,000* | Leap Day โ only exists every 4 years |
| 2 | December 25 | 6,574 | Christmas Day โ no scheduled procedures |
| 3 | January 1 | 7,792 | New Year's Day |
| 4 | December 24 | 8,069 | Christmas Eve |
| 5 | July 4 | 8,796 | Independence Day |
| 6 | January 2 | 9,307 | Day after New Year's |
| 7 | December 26 | 9,543 | Day after Christmas |
| 8 | November 27 | 9,718 | Near Thanksgiving (floating) |
| 9 | November 23 | 9,883 | Near Thanksgiving (floating) |
| 10 | October 31 | 9,978 | Halloween |
| 11 | November 25 | 9,954 | Near Thanksgiving |
| 12 | December 31 | 10,080 | New Year's Eve |
| 13 | January 3 | 10,156 | Post-holiday slowdown |
| 14 | November 28 | 10,200 | Near Thanksgiving |
| 15 | November 24 | 10,245 | Near Thanksgiving |
| 16 | April 1 | 10,312 | April Fool's Day โ cultural avoidance |
| 17 | November 22 | 10,356 | Near Thanksgiving |
| 18 | December 27 | 10,402 | Holiday week |
| 19 | January 4 | 10,456 | Post-holiday |
| 20 | December 23 | 10,510 | Pre-Christmas slowdown |
The September Phenomenon
Nine of the ten most common birthdays fall between September 9 and September 20. This isn't coincidence โ counting back 9 months lands squarely in the December holiday season, when couples spend more time together indoors. Research also suggests male fertility peaks in colder months with improved sperm quality. The one non-September date in the top 10 is July 7, likely due to post-Independence Day scheduling of delayed procedures.
Leap Day Babies: The Rarest of All
People born on February 29 โ called "Leaplings" or "Leapers" โ have a 1 in 1,461 chance of being born on that date. Roughly 5 million people worldwide have a February 29 birthday. In non-leap years, Leaplings typically celebrate on either February 28 or March 1, with no universal standard. Some countries legally assign March 1, while others use February 28. Leap Day babies include motivational speaker Tony Robbins and rapper Ja Rule.
Birthday Rarity Around the World
Birthday patterns differ by country based on local holidays and cultural factors:
In Japan, the rarest birthday is January 1 (very few scheduled births on New Year's). The most common falls in late September, similar to the US pattern.
In India, birth timing correlates with auspicious dates in the Hindu calendar. Some families specifically request C-sections on dates considered lucky.
In UK, the pattern mirrors the US with Christmas Day as the rarest and late September as the peak, though September 26 is the UK's most common birthday.
In Turkey, January 1 shows an unusual spike because births with unknown dates are officially recorded as January 1, making it appear artificially common.
โญ Surprising Birthday Facts
โ Rarest and Most Common Birthdays: FAQ
What is the rarest birthday?
February 29 (Leap Day) is the rarest birthday because it only exists every four years. Among regular dates, December 25 is the rarest at about 6,574 US births a year on average, followed by January 1 (7,792) and December 24 (8,069).
What is the most common birthday?
September 9 is the most common birthday in the US, at about 12,301 births a year on average, followed by September 19 and September 12. Nine of the ten most common dates fall in September; the exception is July 7. You can look up any date in the birthday rarity calculator.
Why are Christmas and New Year's Day such rare birthdays?
Scheduled C-sections and inductions are rarely booked on holidays, so far fewer babies are born on December 25, January 1 and the days around them.
Which month has the most birthdays?
August has the most total births of any month, even though September holds most of the individual days in the top ten. Your birth month also sets your sign; see the rarest zodiac sign or work out yours in the zodiac birth chart.
What are the odds of being born on February 29?
About 1 in 1,461. Roughly 5 million people worldwide have a February 29 birthday. To work out your exact age from any birth date, use the age calculator.
Related Rarity Guides
Scheduled Births Have Kept Growing Since 2014
The 1994โ2014 averages capture a scheduling system that has kept expanding since. NCHS Data Brief No. 554 (March 2026) reports that labor was induced in 34.5% of singleton births in 2024, up from 24.9% in 2016, a 39% increase in eight years. The climb was fastest from 2017 to 2020, near 6% a year, and has run about 2% a year since. Births: Final Data for 2024 puts the cesarean rate at 32.4%, up by less than 1% from 2023, so inductions, not surgery, are driving the change. Not every induction or cesarean is booked in advance, but the planned ones are what empty the calendar on December 25. A larger share of scheduled births should, if anything, deepen the gap between a holiday and a fully staffed weekday. For a baby born in the 2020s, Christmas Day is likely at least as unusual a birthday as the longer-run averages suggest.
The same mechanism explains why the rarest few dates are fixed while later ones are looser. December 25 is in a class of its own, averaging about 6,600 births against roughly 11,100 on a typical day, some 41% lower. After that the margins shrink fast. Halloween and November 25 averaged 9,978 and 9,954 births, a gap of 24, or a quarter of one percent, and less than 6% separates the tenth-quietest date from the twentieth. Weekday effects are far larger: across the same years an average Tuesday saw about 12,800 births and an average Sunday about 7,600. Beyond the first handful, the most useful reading of a rare date is "this falls in the quiet zone" rather than an exact place in line.
Same Date, Different Year, Different Rarity
A calendar date moves forward one weekday each year, or two after a leap day. The weekend dip works the same way as the holiday dip, because inductions and cesareans are booked for fully staffed weekdays, so one birthday can be busy one year and quiet the next. July 4 shows this clearly: from 1994 to 2014, an Independence Day that fell on a Tuesday, Wednesday or Thursday averaged about 9,300 births, while one that landed on a weekend drew between roughly 7,300 and 8,400.
Floating holidays make the effect even more visible. Six of the seven dates from November 22 to 28 rank among the twenty quietest birthdays, even though no year has six Thanksgivings. The holiday is the fourth Thursday of November, so it can land on any date from the 22nd to the 28th. Averaging two decades spreads one deep annual dip, along with the quiet Friday after it, across the whole week. November 24 is a good example: it logged 6,894 births in 2011, when it was Thanksgiving, and 13,907 in 2009, when it was an ordinary Tuesday. Its place among the rarest dates is an average of years like both.
The Peak Used to Move With Latitude
The tight September cluster is a feature of recent US decades, not a biological constant. Martinez-Bakker and colleagues analyzed monthly state-level births from 1931 to 2008 (Proceedings of the Royal Society B, 2014) and found that the timing of the peak followed a northโsouth gradient. Between 1931 and 1945, births peaked as early as June in Oregon and Maine and as late as November in Florida. That left the most out-of-phase states more than five months apart within one country. The seasonal swing was more than twice as large in southern states as in northern ones, and latitude explained 29% to 53% of the variation in its size.
From the baby boom onward, most states peaked in August or later. During the boom itself only seven northern states peaked earlier, and Florida stayed the latest in every era, its own peak drifting earlier from November to October. The spread in timing narrowed but never disappeared. One practical implication: people born in the 1930s and early 1940s arrived under a pattern that differed from state to state, so the December-conception explanation fits their generation less neatly. The date-by-date picture from recent decades reflects today's seasonal habits and hospital scheduling, and it will hold only as long as those do.