Which weekday has the most births?
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- Tuesdaybusiest weekday13,122 births per day
- Sundayquietest weekday7,518 births per day
- 63%weekend levelof weekday births per day
- 5,479consecutive days2000–2014, one source
The U.S. daily file for 2000 to 2014 holds 5,479 consecutive days and 62,187,024 recorded births. Across them Tuesday records the most births, at 115.6 of an average day, and Sunday the fewest, at 66.2. A Tuesday records about 74.5% more births than a Sunday. The weekday figures below stand on their own.
The seven weekdays
This page uses the Social Security Administration daily file on its own. The combined 1994–2014 collection used elsewhere on the site joins two administrative sources at the year 2000, and a weekday average built across that join would mix them. 2000–2014 is 15 complete consecutive years recorded the same way throughout. Every figure below is a mean per occurrence, so a weekday seen 782 times and one seen 783 times are directly comparable.
Births per day by weekday, U.S. 2000–2014
Seven columns, Monday to Sunday, mean recorded births per observed day, with the average day drawn as a line.
| Weekday | Days observed | Births per day | Index (100 = average day) | |
|---|---|---|---|---|
| Tuesday | 783 | 13,122 | 115.6 | |
| Wednesday | 783 | 12,911 | 113.8 | |
| Thursday | 782 | 12,846 | 113.2 | |
| Friday | 782 | 12,596 | 111.0 | |
| Monday | 783 | 11,898 | 104.8 | |
| Saturday | 783 | 8,563 | 75.4 | |
| Sunday | 783 | 7,518 | 66.2 |
The arithmetic is checkable line by line: 62,187,024 recorded births over 5,479 days is 11,350 on an average day, Tuesday is 10,274,874 over 783 occurrences (13122.4444 a day) and Sunday is 5,886,889 over 783 (7518.3768). Every figure on this page is recomputed from the file at build time.
Taken as two groups, a weekend day records 8,040 births and a working day 12,675, a ratio of 0.6344. Both groups are observed a different number of times, so this is computed from the days themselves.
All five working days are above the average day and both weekend days well below it. The weekday is derived from each record's calendar date, and a row whose stated weekday disagrees with its date is rejected before anything is computed.
Is the gap steady?
Each year below is measured against its own average day. In 2000 the weekend level was 75.3; in 2014 it was 71.7, a change of -3.5 points.
Weekend and weekday level by year, 2000–2014 (100 = that year’s average day)
Two lines, one point per year: Saturday and Sunday births per day against the year’s average day, and Monday to Friday against the same.
| Year | Weekend index | Weekday index | Sunday index | |
|---|---|---|---|---|
| 2000 | 75.3 | 110.1 | 70.7 | |
| 2001 | 74.0 | 110.4 | 69.0 | |
| 2002 | 72.8 | 110.8 | 68.1 | |
| 2003 | 71.9 | 111.2 | 67.3 | |
| 2004 | 71.0 | 111.5 | 66.5 | |
| 2005 | 69.6 | 112.3 | 64.8 | |
| 2006 | 69.6 | 112.3 | 64.7 | |
| 2007 | 69.5 | 112.1 | 64.7 | |
| 2008 | 69.3 | 112.2 | 64.7 | |
| 2009 | 68.7 | 112.5 | 64.3 | |
| 2010 | 68.7 | 112.5 | 64.7 | |
| 2011 | 69.3 | 112.4 | 64.8 | |
| 2012 | 70.4 | 111.9 | 65.8 | |
| 2013 | 71.0 | 111.6 | 66.5 | |
| 2014 | 71.7 | 111.3 | 67.3 |
Months, on the same file
Months are compared per observed day.
| Month | Days observed | Births per day | Index (100 = average day) | |
|---|---|---|---|---|
| January | 465 | 10,909 | 96.1 | |
| February | 424 | 11,146 | 98.2 | |
| March | 465 | 11,125 | 98.0 | |
| April | 450 | 11,024 | 97.1 | |
| May | 465 | 11,173 | 98.4 | |
| June | 450 | 11,474 | 101.1 | |
| July | 465 | 11,721 | 103.3 | |
| August | 465 | 11,914 | 105.0 | |
| September | 450 | 11,999 | 105.7 | |
| October | 465 | 11,404 | 100.5 | |
| November | 450 | 11,131 | 98.1 | |
| December | 465 | 11,171 | 98.4 |
Ranked by raw total, the order changes: August has the largest number of recorded births (5,540,170), while September has the highest average per observed day (11,999). Month length is the whole of that difference, which is why the table above is per day.
September is the busiest month at 105.7 and January the quietest at 96.1. The spread between months, 9.6 points, is far smaller than the spread between weekdays, 49.4 points.
Why this matters for a birthday ranking
Over many years a calendar date falls on every weekday; inside a short window the mix is uneven, and holidays fall on fixed weekdays or fixed dates. A date that often fell on a weekend or a holiday in a given period will look quiet, and one that mostly fell midweek will look busy, before anything about the date itself is considered. That is why every per-date figure on this site states its window, and why the holiday study compares each holiday with the same weekday nearby.
Lower weekend counts are consistent with scheduled inductions and caesareans concentrating on working days, with staffing, and with recording practice. Daily totals hold the count alone.
About the other SSA files
The Social Security Administration also publishes baby-name data, which is a different thing: names by year, sex and state, with names used fewer than five times suppressed. Those files hold names by year; the daily series here ends at 2014.
Check your own birthday → · Month ranking · All 366 dates
Sources, method and limits
Source: Social Security Administration daily birth counts for the United States, 2000–2014, as compiled by FiveThirtyEight and attributed under CC BY 4.0. 5,479 daily rows, all 15 years complete, each row validated for a real calendar date, a matching weekday, a whole count of zero or more and one row per date before use. This page uses the SSA years alone.
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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