How common are September birthdays?
- 11,811births per day#1 of 12 months
- 8.7%of all births in the sample7,440,659 recorded
- September 9most common September date#1 of 366
- September 1quietest date that occurs every year#255 of 366
September is the most common birth month of the 12, at 11,811 recorded births per day, 5.7% above an average day across 85,712,738 U.S. births from 1994–2014. Its most common date is September 9 (#1 of 366) and its quietest date that occurs every year is September 1 (#255).
Every date is coloured by the same six rarity tiers the reveal uses; the small number is its rank of 366 from most common.
- 1#255
- 2#222
- 3#177
- 4#142
- 5#102
- 6#123
- 7#106
- 8#13
- 9#1
- 10#5
- 11#91
- 12#3
- 13#33
- 14#25
- 15#8
- 16#9
- 17#4
- 18#10
- 19#2
- 20#6
- 21#32
- 22#22
- 23#14
- 24#18
- 25#24
- 26#12
- 27#27
- 28#84
- 29#79
- 30#95
Every September date: recorded U.S. births 1994–2014
One column per September date in calendar order, coloured by rarity tier, total recorded births 1994–2014.
Every September date, ranked
Ranked by total recorded births across the 21 years, the same measure as the site-wide rank of 366.
| Date | Total births | Rank of 366 | Odds | |
|---|---|---|---|---|
| September 9 | 259,228 | #1 | 1 in 331 | |
| September 19 | 257,981 | #2 | 1 in 332 | |
| September 12 | 257,913 | #3 | 1 in 332 | |
| September 17 | 256,231 | #4 | 1 in 335 | |
| September 10 | 255,991 | #5 | 1 in 335 | |
| September 20 | 255,392 | #6 | 1 in 336 | |
| September 15 | 254,652 | #8 | 1 in 337 | |
| September 16 | 254,393 | #9 | 1 in 337 | |
| September 18 | 254,350 | #10 | 1 in 337 | |
| September 26 | 252,994 | #12 | 1 in 339 | |
| September 8 | 252,605 | #13 | 1 in 339 | |
| September 23 | 252,362 | #14 | 1 in 340 | |
| September 24 | 251,853 | #18 | 1 in 340 | |
| September 22 | 251,168 | #22 | 1 in 341 | |
| September 25 | 250,348 | #24 | 1 in 342 | |
| September 14 | 250,282 | #25 | 1 in 342 | |
| September 27 | 250,029 | #27 | 1 in 343 | |
| September 21 | 248,978 | #32 | 1 in 344 | |
| September 13 | 248,851 | #33 | 1 in 344 | |
| September 29 | 243,883 | #79 | 1 in 351 | |
| September 28 | 243,476 | #84 | 1 in 352 | |
| September 11 | 242,785 | #91 | 1 in 353 | |
| September 30 | 242,161 | #95 | 1 in 354 | |
| September 5 | 241,264 | #102 | 1 in 355 | |
| September 7 | 240,167 | #106 | 1 in 357 | |
| September 6 | 238,193 | #123 | 1 in 360 | |
| September 4 | 236,602 | #142 | 1 in 362 | |
| September 3 | 234,424 | #177 | 1 in 366 | |
| September 2 | 231,887 | #222 | 1 in 370 | |
| September 1 | 230,216 | #255 | 1 in 372 |
September in the year
September has 8.68% of all recorded births in this sample, over 630 observed days. Months are ranked by births per day. On that measure it is the top month; January is at the bottom (10,721 per day). Full month ranking.
Keep going
Check how rare your own birthday is →
Sources, method and limits
Main ranking: 85,712,738 recorded U.S. births on 7,670 calendar dates, 1994–2014. CDC/NCHS daily counts for 1994–1999 and Social Security Administration daily counts for 2000–2014, as compiled by FiveThirtyEight and attributed under CC BY 4.0. The overlapping years 2000–2003 are counted once.
Ranks compare totals across the 366 observed month-and-day dates. February 29 occurred 5 times in this window; every other date occurred 21 times, so per-occurrence figures are used wherever seasonality is compared.
Every figure above comes from the administrative records named here, at the granularity those records publish: a day, a month or a year. Coverage and definitions differ between countries and eras, so two sources are combined only where their documentation states the windows are separate, and the page where that happens says so.
Full method, leap-day treatment and definitions.
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