What is the most common birthday? September 9

About 11,900 births a year in the United States, 10% above an average day. Fifteen of the twenty most common birthdays are in September.

  1. Sep 9#1
  2. Sep 20#2
  3. Sep 19#3
  4. Sep 14#4
  5. Jul 7#5
Six children in party hats along one table, each blowing out the candles on an identical birthday cake
The top of the calendar

The twenty most common birthdays

Fifteen in September, two in August, two in December and one in July. All twenty fall between July 7 and December 28.

  1. #1September 911,900+9.7%
  2. #2September 2011,824+9.0%
  3. #3September 1911,800+8.8%
  4. #4September 1411,790+8.7%
  5. #5July 711,784+8.7%
  6. #6December 2811,779+8.6%
  7. #7September 1211,766+8.5%
  8. #8September 1011,740+8.3%
  9. #9September 1811,736+8.2%
  10. #10September 2111,731+8.2%
  1. #11September 1511,710+8.0%
  2. #12September 1711,706+7.9%
  3. #13September 1611,671+7.6%
  4. #14September 811,635+7.3%
  5. #15December 2011,622+7.2%
  6. #16August 1611,599+7.0%
  7. #17September 2211,582+6.8%
  8. #18August 811,579+6.8%
  9. #19September 2711,579+6.8%
  10. #20September 1311,562+6.6%
The reason

Why September 9

Count back thirty-eight weeks from September 9 and you land on December 17: the week of the winter holidays.

  • Why that week. It is the one stretch of the year when most people are off work together, celebrating, and in much of the country it is cold enough to stay in.
  • A slope, not a spike. September 9 is #1 by a whisker: four other dates sit within 1% of its count, and fifteen of the twenty most common birthdays sit between September 8 and September 27.
  • The other end. Christmas Day, New Year's Day and the Fourth of July are the days hospitals postpone every delivery they can. December 25, the rarest birthday, sees 1.8 times fewer births than September 9.
At a glance

September 9 in numbers

The peak is a ridge through the middle of September, with an ordinary August on one side and an ordinary October on the other.

September 9 is the top of a slope, not a spike

September 9#1 of 366 · 11,900 births a year
1 in 333American babies are born on September 9
1,020,000Americans alive today were born on September 9, by our estimate
1.8×as many births as on December 25, the rarest birthday
Around the world

15 of 27 countries peak in September

From September 8 in the Philippines to September 27 in Ireland and New Zealand. The other 12 peak elsewhere in the year, from January 3 in Argentina to December 27 in Chile.

PlaceMost common birthdayBirthdayBirths a yearBirthsRecords
Americas
United StatesSeptember 911,900NCHS, 1989–⁠2024
ArgentinaJanuary 31,832DEIS, 2018–⁠2023
BrazilMarch 108,843DATASUS, 1997–⁠2024
ChileDecember 27813DEIS, 1990–⁠2017
Costa RicaSeptember 19196INEC Costa Rica, 2014–⁠2024
EcuadorFebruary 14882INEC, 2013–⁠2023
GuatemalaSeptember 201,115INE Guatemala, 2018–⁠2024
MexicoSeptember 146,235INEGI, 2017–⁠2023
PeruMarch 51,310INEI, 2019–⁠2025
Europe
BelgiumJuly 23352Statbel, 1992–⁠2025
DenmarkAugust 18184Statistics Denmark, 2007–⁠2025
England & WalesSeptember 261,927ONS, 1995–⁠2025
FinlandSeptember 20158Statistics Finland, 2010–⁠2025
FranceSeptember 202,290INSEE, 1998–⁠2024
GermanyAugust 82,314Destatis, 2014–⁠2025
HungaryJuly 25359KSH, 1970–⁠2020
IrelandSeptember 27186CSO, 1980–⁠2023
LatviaJune 1962CSB, 1996–⁠2025
NetherlandsSeptember 24549CBS, 1995–⁠2025
NorwayJune 28180SSB, 2011–⁠2025
PortugalSeptember 16330INE Portugal, 1980–⁠2025
SloveniaSeptember 2062SURS, 2000–⁠2025
SwitzerlandSeptember 25243FSO, 1969–⁠2025
Asia & Pacific
JapanSeptember 253,189e-Stat, 1996–⁠2025
MalaysiaOctober 101,565DOSM, 2000–⁠2022
New ZealandSeptember 27172Stats NZ, 1980–⁠2023
PhilippinesSeptember 85,587PSA, 2006–⁠2024
The long list

The 100 most common birthdays

Of the 100, 30 are August dates, 27 are July dates and 23 are September dates; eight more are December dates on either side of Christmas.

  1. #1September 911,900
  2. #2September 2011,824
  3. #3September 1911,800
  4. #4September 1411,790
  5. #5July 711,784
  6. #6December 2811,779
  7. #7September 1211,766
  8. #8September 1011,740
  9. #9September 1811,736
  10. #10September 2111,731
  11. #11September 1511,710
  12. #12September 1711,706
  13. #13September 1611,671
  14. #14September 811,635
  15. #15December 2011,622
  16. #16August 1611,599
  17. #17September 2211,582
  18. #18August 811,579
  19. #19September 2711,579
  20. #20September 1311,562
  21. #21September 2311,559
  22. #22September 2511,546
  23. #23August 3011,546
  24. #24December 2911,535
  25. #25September 2611,534
  26. #26July 811,531
  27. #27August 1511,528
  28. #28September 2411,527
  29. #29December 2111,521
  30. #30August 1711,519
  31. #31August 2811,515
  32. #32August 911,511
  33. #33August 3111,504
  34. #34August 1011,487
  35. #35July 111,480
  36. #36August 2911,479
  37. #37December 3011,459
  38. #38August 2311,451
  39. #39August 2211,450
  40. #40August 2411,447
  41. #41July 1011,443
  42. #42July 611,443
  43. #43August 1411,438
  44. #44July 2711,430
  45. #45September 2811,428
  46. #46July 211,419
  47. #47July 1711,414
  48. #48August 1811,413
  49. #49July 1111,404
  50. #50August 211,401
  51. #51July 2511,400
  52. #52August 111,399
  53. #53July 2011,396
  54. #54August 1211,393
  55. #55August 2011,391
  56. #56December 2711,389
  57. #57July 911,381
  58. #58August 2111,381
  59. #59July 2611,377
  60. #60July 1811,368
  61. #61December 1911,366
  62. #62July 1511,355
  63. #63August 311,346
  64. #64July 2111,343
  65. #65July 1611,338
  66. #66August 711,338
  67. #67July 1411,334
  68. #68July 1211,333
  69. #69July 1911,329
  70. #70August 2711,328
  71. #71October 111,326
  72. #72August 1111,322
  73. #73June 2811,320
  74. #74July 2411,318
  75. #75August 1911,318
  76. #76July 2811,317
  77. #77July 2211,315
  78. #78July 2311,314
  79. #79October 211,302
  80. #80October 411,291
  81. #81August 411,289
  82. #82October 311,284
  83. #83August 2511,281
  84. #84August 511,275
  85. #85December 1811,273
  86. #86June 2911,264
  87. #87July 2911,260
  88. #88August 2611,253
  89. #89August 611,238
  90. #90October 511,236
  91. #91July 3011,233
  92. #92July 3111,229
  93. #93June 3011,224
  94. #94February 1411,222
  95. #95September 2911,210
  96. #96September 711,202
  97. #97June 2711,184
  98. #98September 1111,167
  99. #99June 111,152
  100. #100October 1011,142
Questions

Quick answers

What is the most common birthday?

September 9, in the United States: about 11,900 births in an average year, +9.7% against an average day. Fifteen of the twenty most common birthdays fall in September.

Why are so many birthdays in September?

Because of when people conceive. Thirty-eight weeks before September 9 is December 17, the middle of the winter holidays. The result is a slope that climbs through late August, crests in mid-September and eases through October, not one crowded day.

How many people share the most common birthday?

About 1 in every 333 births in the United States lands on September 9, and roughly 1,020,000 Americans alive today were born on it. In a room of 333, expect one.

Is the most common birthday the same in every country?

No. 15 of the 27 countries we hold records for peak in September, from September 8 in the Philippines to September 27 in Ireland and New Zealand. The other 12 peak elsewhere in the year: Argentina on January 3, Ecuador on February 14, Peru on March 5, Brazil on March 10, Latvia on June 19, Norway on June 28, Belgium on July 23, Hungary on July 25, Germany on August 8, Denmark on August 18, Malaysia on October 10 and Chile on December 27.

What is the rarest birthday?

December 25, with about 6,546 births a year, 1.8 times fewer than September 9. The rarest dates are the holidays hospitals can postpone.

So, how rare is yours?

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