birthday traffic

How common are January birthdays?

Published by Birthday Traffic · · Sources and method

January is the least common birth month of the 12, at 10,721 recorded births per day, 4.1% below an average day across 85,712,738 U.S. births from 1994–2014. Its most common date is January 24 (#200 of 366) and its quietest date that occurs every year is January 1 (#364).

Every date is coloured by the same six rarity tiers the reveal uses; the small number is its rank of 366 from most common.

Every January date: recorded U.S. births 1994–2014

One column per January date in calendar order, coloured by rarity tier, total recorded births 1994–2014.

Every January date: recorded U.S. births 1994–2014One column per January date in calendar order, coloured by rarity tier, total recorded births 1994–2014.050,000100,000150,000200,000250,0001: 164,362164,36212: 196,4813: 228,2594: 232,3545: 230,82656: 229,7767: 230,2338: 223,7669: 224,116910: 232,52111: 231,41412: 230,49913: 223,8031314: 231,34315: 222,37416: 224,05517: 230,0381718: 229,46519: 225,38720: 228,13821: 228,1902122: 225,09823: 229,16324: 233,021233,02125: 230,8972526: 228,39427: 228,01228: 228,36529: 222,8312930: 226,66931: 229,472
Calendar order; each column is the date’s total across the window, in its rarity colour.

Every January date, ranked

Ranked by total recorded births across the 21 years, the same measure as the site-wide rank of 366.

Recorded U.S. births per January date, 1994–2014
DateTotal birthsRank of 366Odds
January 24233,021#2001 in 368
January 10232,521#2051 in 369
January 4232,354#2071 in 369
January 11231,414#2271 in 370
January 14231,343#2301 in 371
January 25230,897#2381 in 371
January 5230,826#2411 in 371
January 12230,499#2471 in 372
January 7230,233#2541 in 372
January 17230,038#2581 in 373
January 6229,776#2681 in 373
January 31229,472#2781 in 374
January 18229,465#2791 in 374
January 23229,163#2831 in 374
January 26228,394#2961 in 375
January 28228,365#2971 in 375
January 3228,259#3011 in 376
January 21228,190#3021 in 376
January 20228,138#3031 in 376
January 27228,012#3051 in 376
January 30226,669#3191 in 378
January 19225,387#3301 in 380
January 22225,098#3341 in 381
January 9224,116#3391 in 382
January 16224,055#3401 in 383
January 13223,803#3421 in 383
January 8223,766#3431 in 383
January 29222,831#3451 in 385
January 15222,374#3461 in 385
January 2196,481#3611 in 436
January 1164,362#3641 in 521

January in the year

January has 8.14% of all recorded births in this sample, over 651 observed days. Months are ranked by births per day. On that measure it is last of the 12; September is at the top (11,811 per day). Full month ranking.

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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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