How common is a March 21 birthday?
March 21
Common
More common than 59.5%of other birthday dates.
1 in 363births in this sample share your birthday.
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March 21 is the 149th most common birthday of the 366 dates in this collection, and the 218th rarest. It records 235,883 births out of 85,712,738, so roughly 1 in 363 people in this sample were born on it.
It is more common than 59.5% of the other 365 dates and rarer than 40.5%. It records 100.5% of an average day’s count in the sample.
March 21 among all 366 dates
All 366 dates sorted from most to least common by recorded U.S. births 1994–2014, coloured by rarity tier, with March 21 marked.
March 21 against the days around it
| Date | Total births | Rank of 366 | |
|---|---|---|---|
| March 18 | 230,793 | #242 | |
| March 19 | 230,048 | #257 | |
| March 20 | 232,226 | #209 | |
| March 21 (this date) | 235,883 | #149 | |
| March 22 | 231,059 | #235 | |
| March 23 | 226,193 | #323 | |
| March 24 | 229,992 | #259 |
March as a whole records 10,979 births per day, ranked #9 of 12 months. Month ranking · March 20 · March 22
Has March 21 changed over time?
Annual U.S. birth totals changed across this window, so a raw daily count moves with the size of the year. The chart uses each year's share of that year's births instead, in births per 100,000. Averaged over the first five observed years it is 282.3 per 100,000; over the last five, 274.3 per 100,000 (-2.8%).
March 21 as a share of each year’s U.S. births, 1994–2014
Births on March 21 per 100,000 births in that year, one point per year, with the change of source at 2000 marked and the first-five and last-five year means drawn as bands.
| Year | Births on this date | Per 100,000 births | |
|---|---|---|---|
| 1994 | 11,140 | 281.8 | |
| 1995 | 11,837 | 303.5 | |
| 1996 | 11,653 | 299.4 | |
| 1997 | 11,846 | 305.2 | |
| 1998 | 8,730 | 221.5 | |
| 1999 | 7,582 | 191.5 | |
| 2000 | 12,689 | 305.8 | |
| 2001 | 12,690 | 308.7 | |
| 2002 | 12,502 | 305.0 | |
| 2003 | 12,653 | 303.9 | |
| 2004 | 7,548 | 180.3 | |
| 2005 | 12,108 | 287.5 | |
| 2006 | 13,378 | 308.6 | |
| 2007 | 13,710 | 313.0 | |
| 2008 | 12,606 | 292.4 | |
| 2009 | 8,286 | 197.7 | |
| 2010 | 6,992 | 172.4 | |
| 2011 | 11,794 | 294.3 | |
| 2012 | 12,056 | 301.3 | |
| 2013 | 12,096 | 304.4 | |
| 2014 | 11,987 | 298.9 |
Source break: 1994–1999 counts come from the CDC/NCHS daily file and 2000–2014 from the Social Security Administration daily file. The overlapping years 2000–2003 are taken from the SSA file only, so each year is counted once. But the step at 2000 is a change of source as well as a change of year, and any comparison across it includes that change.
The weekday the date fell on, scheduling practice and recording practice are all inside these lines.
A generation earlier, in the separate daily file for 1969–1988, March 21 ranked #236 of 366 with 9,446 births per occurrence. The 1969–1988 calendar and what changed since.
March 21 in five countries
Countries are compared only over the matched years 2007–2014, which all five sources cover completely, and using births per occurrence so that leap day is handled the same way everywhere. Each country's records are counted on their own.
| Country | Rank of 366 | Index (100 = average day) | |
|---|---|---|---|
| United States | #204 | 99.3 | |
| England & Wales | #309 | 97.1 | |
| Denmark | #226 | 98.5 | |
| Metropolitan France | #300 | 96.7 | |
| Malaysia | #193 | 99.5 |
In the matched window the U.S. rank is #204; over the full 1994–2014 collection it is #149. The two numbers answer different questions and usually differ for two reasons at once: the window is eight years against twenty-one, and the metric is births per occurrence against the total across the whole period. Every figure on this page names its window and its metric. Full five-country study.
Among the 6,025,603 people living in Denmark on January 1, 2026, 18,312 have this birthday, one resident in 329. A count of people living there, wherever they were born. How many people in Denmark share a birthday.
Born on March 21
12 people from the English Wikipedia “On this day” birth lists, oldest first. A reading list. Every birth figure on this page comes from the national records.
- Scott Fahlman1948American computer scientist
- Steve Furber1953English computer scientist
- Nobuo Uematsu1959Japanese composer
- Kassie DePaiva1961American actress and singer
- Scott Williams1968American basketball player
- Fabricio Oberto1975Argentine-Italian basketball player
- Mark Williams1975Welsh snooker player
- Vitaly Potapenko1975Ukrainian basketball player
- Adrian Peterson1985American football player
- Solomon Alabi1988Nigerian basketball player
- Chiney Ogwumike1992Nigerian-American basketball player
- Kristýna Plíšková1992Czech tennis player
Names and descriptions from English Wikipedia, CC BY-SA 4.0, retrieved 2026-09-11; curated arts/science/sport entries, years 1800–2008. not a celebrity census. conflicting identities excluded.
Keep going
- ← March 20
- March 22 →
- All March birthdays
- All 366 dates
- Most common birthday
- Least common birthday
- Explore the whole calendar
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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