September 1 had the fewest births among September dates in these U.S. records from 1994 through 2014: 230,216. September 9 had the most, with 259,228. The chart and table cover all 30 dates.
Compare September birthdays
September 1 had the fewest births and September 9 the most among September dates in these U.S. records. Choose two dates to see how far apart they are.
CDC/NCHS + SSA via FiveThirtyEight · 1994–2014 · 85,712,738 births
September 1
- Within September
- #30 of 30
- Across the whole year
- #255 of 366
- Recorded births
- 230,216
- Share of all births
- 0.269%
Both ranks count from most common (#1) to rarest. Ties share a rank.
September 1 had 11.2% fewer births than September 9 (230,216 versus 259,228).
Open September 1 in the birthday checkerAll 30 September birthdays ranked
Month rank compares only September dates. Overall rank compares all 366 dates, including February 29. #1 is most common in both columns.
| Date | Month rank | Overall rank | Births | Share of all births |
|---|---|---|---|---|
| September 1 | #30 | #255 | 230,216 | 0.269% |
| September 2 | #29 | #222 | 231,887 | 0.271% |
| September 3 | #28 | #177 | 234,424 | 0.273% |
| September 4 | #27 | #142 | 236,602 | 0.276% |
| September 5 | #24 | #102 | 241,264 | 0.281% |
| September 6 | #26 | #123 | 238,193 | 0.278% |
| September 7 | #25 | #106 | 240,167 | 0.280% |
| September 8 | #11 | #13 | 252,605 | 0.295% |
| September 9 | #1 | #1 | 259,228 | 0.302% |
| September 10 | #5 | #5 | 255,991 | 0.299% |
| September 11 | #22 | #91 | 242,785 | 0.283% |
| September 12 | #3 | #3 | 257,913 | 0.301% |
| September 13 | #19 | #33 | 248,851 | 0.290% |
| September 14 | #16 | #25 | 250,282 | 0.292% |
| September 15 | #7 | #8 | 254,652 | 0.297% |
| September 16 | #8 | #9 | 254,393 | 0.297% |
| September 17 | #4 | #4 | 256,231 | 0.299% |
| September 18 | #9 | #10 | 254,350 | 0.297% |
| September 19 | #2 | #2 | 257,981 | 0.301% |
| September 20 | #6 | #6 | 255,392 | 0.298% |
| September 21 | #18 | #32 | 248,978 | 0.290% |
| September 22 | #14 | #22 | 251,168 | 0.293% |
| September 23 | #12 | #14 | 252,362 | 0.294% |
| September 24 | #13 | #18 | 251,853 | 0.294% |
| September 25 | #15 | #24 | 250,348 | 0.292% |
| September 26 | #10 | #12 | 252,994 | 0.295% |
| September 27 | #17 | #27 | 250,029 | 0.292% |
| September 28 | #21 | #84 | 243,476 | 0.284% |
| September 29 | #20 | #79 | 243,883 | 0.285% |
| September 30 | #23 | #95 | 242,161 | 0.283% |
Each September date occurs 21 times in this period, so ranking by births per occurrence gives the same order within this month.
Is September 1 a rare birthday?
Within September, yes. September 1 ranks #30 of 30 by recorded births. Across all 366 birthday dates, it ranks #255. In both lists, #1 means the most births.
How different is September's first week?
September 1 through 7 are the month's 7 lowest-total dates. Together they had 1,652,753 births, compared with 1,767,655 for September 8 through 14. The first week had 6.5% fewer births and was lower in 21 of 21 years.
Both seven-day blocks contain every weekday once in each year, so the gap does not come from one block having more weekends. Labor Day falls in the first block, but these records cannot separate the holiday from other differences between the weeks or tell us why births fell on particular dates.
Which September birthday is most common?
September 9 ranks #1 within September and among all 366 dates in this dataset. Its 259,228 births are 12.6% above September 1's total. The most-common-birthday guide explains September 9's place in the all-year ranking.
How to read the table
The September rank compares 30 dates and the overall rank compares 366. Both sort by total recorded births. Every September date occurred 21 times, so births per occurrence would produce the same order within the month. Birth share divides each date's total by all recorded births in the dataset.
Compare dates in the tool above. For a date outside September, use the birthday checker. The rarest-birthday ranking covers all 366 dates, and the birth-month guide compares whole months.
Sources and limits
These counts come from daily U.S. birth files compiled by FiveThirtyEight. We use CDC/NCHS records from 1994 through 1999 and SSA records from 2000 through 2014, excluding the overlapping CDC years. September contributes 7,440,659 births in this dataset.
The two sources have different administrative coverage. The results describe historical U.S. births, not the world's births, current births, or everyone alive with a September birthday. The methodology explains the source selection and ranks.
Reviewed