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Most common birthdays: how common is yours?

The most common birthday in the US is September 9. About 12,301 babies were born on an average September 9 from 1994 to 2014, 10.5% more than an average day.

The rarest is February 29, which comes once every four years. Among everyday dates, December 25 is the rarest, with about 6,574 births, 40.9% fewer than an average day.

By the InviteBird team · Updated October 24, 2026

September 9

1st of 366 dates by births per day

More births per day than
100% of the other 365 dates
Births on an average September 9
12,301 (+10.5% vs an average day)
Babies per 100,000 born in a year
about 302.5
Season
Fall

September 9 is the most common birthday in the US.

Every date, 1994–2014. Darker means more births. Tap a date to look it up.

How does the birthday lookup work?

It ranks all 366 dates by the average number of babies born on them. The data covers 21 years of US birth records. It is one of our party planning tools.

  1. Pick a date. Choose a month and day, or tap a square on the heatmap.
  2. Read its rank. 1st has the most births per day and 366th the fewest. February 29 gets its own note: it is the rarest birthday because it comes once in four years.
  3. Compare it. See the average births on that date against an average day of 11,132 births.
  4. Share it. Copy a link to your date, download the chart, or embed the lookup on your site.

Worked examples: three dates

  • September 9 ranks 1st. About 12,301 babies are born on an average September 9, 10.5% more than an average day. That is about 302.5 of every 100,000 babies born in a year.
  • December 25 ranks 366th by births per day. It sees about 6,574 births, 40.9% fewer than an average day. That is about 161.7 per 100,000.
  • February 29 sees about 10,462 births in the leap years it exists, only 6% fewer than an average day. But it comes once in four years, so only about 64.3 of every 100,000 babies share it. That is the fewest of any date.
A paper wall calendar with one square circled in gold, a small birthday cake with a single candle on the desk below it.
Digital illustration. Every date on the calendar is somebody’s birthday; some are shared by far more people than others.

What are the 10 most common birthdays?

September 9 is the most common birthday, and 13 of the 20 most common fall in September.

RankDateAverage births
1September 912,301 (+10.5%)
2September 1912,229 (+9.9%)
3September 1212,224 (+9.8%)
4September 1712,148 (+9.1%)
5September 1012,143 (+9.1%)
6July 712,108 (+8.8%)
7September 2012,107 (+8.8%)
8September 1512,087 (+8.6%)
9September 1612,072 (+8.4%)
10September 1812,055 (+8.3%)

What are the rarest birthdays?

February 29 is the rarest birthday, because it exists only in leap years. Among the other 365 dates, the rarest are holidays and the days around them. Here are the 12 rarest everyday dates.

RankDateAverage births
366December 256,574 (−40.9%)
365January 17,792 (−30%)
364December 248,069 (−27.5%)
363July 48,796 (−21%)
362January 29,307 (−16.4%)
361December 269,543 (−14.3%)
360November 279,718 (−12.7%)
359November 239,883 (−11.2%)
358November 259,954 (−10.6%)
357October 319,978 (−10.4%)
356November 2410,015 (−10%)
355November 2610,044 (−9.8%)

Thanksgiving moves each year, so the late-November dates it often lands on show up here too.

What is the most common birthday month?

September has the most births per day, 5.7% more than an average day.

August has the largest share of a year’s births, 8.9%. That is because it has 31 days to September’s 30. January has the fewest births per day.

The most common August birthday is August 8, ranked 16th, with about 11,951 births on an average August 8.

RankMonthBirths per dayShare of the year
1September11,7648.68%
2August11,6688.9%
3July11,5228.78%
4June11,2678.31%
5October11,1588.51%
6May10,9848.37%
7December10,9428.34%
8March10,9408.34%
9February10,9407.6%
10November10,8818.03%
11April10,8368%
12January10,6788.14%

Why are September birthdays so common?

Births climb through the summer and peak in September, the month with the most births per day. The National Center for Health Statistics describes the same long-run pattern: birth rates peak in summer and drop in late fall and winter. This data shows when babies are born, not why.

Counting back about nine months from mid-September lands in mid-December, which is often given as the reason. The birth records themselves cannot confirm it.

Why are holidays and weekends rare birthdays?

Because many births are scheduled. The National Center for Health Statistics found the weekend dip is much larger for cesarean births, which are more likely to be scheduled. Holidays show the same dip as weekends, which suggests the same reason.

Tuesday is the busiest day for births, with 12,788 a day (+14.9%). Sunday is the quietest, with 7,610 (−31.6%).

DayBirths per dayAgainst an average day
Monday11,563+3.9%
Tuesday12,788+14.9%
Wednesday12,569+12.9%
Thursday12,503+12.3%
Friday12,304+10.5%
Saturday8,593−22.8%
Sunday7,610−31.6%

What is the rarest birthday in the world?

February 29 is the rarest birthday wherever the standard calendar is used, because the date comes around only in leap years. England and Wales show the same pattern.

The Office for National Statistics found that 29 February had the fewest births in total from 1995 to 2014, because it comes around only once every four years. It also found that 6 of the 10 least common birth dates fall over Christmas and New Year, and that 26 September was the most common. The rankings on this page are for the United States only.

How do all 366 birthdays compare?

The chart shows every date at once. Download it for a class, a post or a story; the source line is printed on it.

Heatmap of average US births for every calendar date, 1994 to 2014: dark green across late summer and September, pale cells on Christmas, New Year's Day and the Fourth of July.
Chart. Average US births by calendar date, 1994–2014; darker means more births.
Download the chart (PNG)
All 366 dates as a table
DateRankAgainst an average day
January 1365th−30%
January 2362nd−16.4%
January 3306th−2.9%
January 4209th−1%
January 5237th−1.6%
January 6259th−2%
January 7255th−1.9%
January 8343rd−4.7%
January 9340th−4.6%
January 10207th−1%
January 11230th−1.4%
January 12248th−1.8%
January 13342nd−4.6%
January 14229th−1.4%
January 15346th−5.3%
January 16341st−4.6%
January 17264th−2.1%
January 18278th−2.2%
January 19332nd−4%
January 20301st−2.8%
January 21302nd−2.8%
January 22334th−4.1%
January 23285th−2.4%
January 24199th−0.8%
January 25241st−1.6%
January 26295th−2.6%
January 27303rd−2.8%
January 28297th−2.7%
January 29345th−5.1%
January 30318th−3.4%
January 31279th−2.2%
February 1251st−1.8%
February 2243rd−1.6%
February 3296th−2.6%
February 4261st−2%
February 5333rd−4%
February 6311th−3%
February 7166th+0.1%
February 8195th−0.6%
February 9272nd−2.2%
February 10211th−1.1%
February 11212th−1.1%
February 12269th−2.1%
February 13344th−4.7%
February 1463rd+4.5%
February 15150th+0.5%
February 16244th−1.7%
February 17291st−2.5%
February 18246th−1.7%
February 19335th−4.1%
February 20277th−2.2%
February 21216th−1.1%
February 22182nd−0.2%
February 23253rd−1.8%
February 24262nd−2.1%
February 25232nd−1.4%
February 26325th−3.6%
February 27288th−2.5%
February 28198th−0.7%
February 29 (leap years)347th−6%
March 1174th0%
March 2309th−3%
March 3190th−0.5%
March 4225th−1.3%
March 5227th−1.4%
March 6257th−1.9%
March 7184th−0.4%
March 8228th−1.4%
March 9316th−3.3%
March 10247th−1.7%
March 11249th−1.8%
March 12219th−1.2%
March 13338th−4.3%
March 14179th−0.1%
March 15215th−1.1%
March 16314th−3.2%
March 17169th0%
March 18236th−1.6%
March 19258th−2%
March 20220th−1.2%
March 21153rd+0.4%
March 22233rd−1.5%
March 23322nd−3.5%
March 24256th−1.9%
March 25231st−1.4%
March 26276th−2.2%
March 27271st−2.1%
March 28201st−0.8%
March 29284th−2.3%
March 30329th−3.8%
March 31313th−3.2%
April 1353rd−7.5%
April 2217th−1.1%
April 3268th−2.1%
April 4144th+0.8%
April 5266th−2.1%
April 6339th−4.4%
April 7287th−2.5%
April 8275th−2.2%
April 9298th−2.7%
April 10300th−2.8%
April 11196th−0.7%
April 12238th−1.6%
April 13351st−6.7%
April 14307th−2.9%
April 15281st−2.2%
April 16260th−2%
April 17270th−2.1%
April 18218th−1.2%
April 19274th−2.2%
April 20328th−3.8%
April 21304th−2.8%
April 22283rd−2.3%
April 23286th−2.4%
April 24294th−2.6%
April 25224th−1.2%
April 26282nd−2.2%
April 27336th−4.2%
April 28308th−3%
April 29323rd−3.6%
April 30324th−3.6%
May 1221st−1.2%
May 2181st−0.2%
May 3263rd−2.1%
May 4327th−3.7%
May 5191st−0.5%
May 6242nd−1.6%
May 7245th−1.7%
May 8235th−1.6%
May 9203rd−0.8%
May 10192nd−0.5%
May 11319th−3.5%
May 12210th−1%
May 13330th−3.9%
May 14193rd−0.6%
May 15162nd+0.2%
May 16127th+1.4%
May 17177th−0.1%
May 18267th−2.1%
May 19223rd−1.2%
May 20147th+0.5%
May 21135th+1.1%
May 22126th+1.4%
May 2389th+3.5%
May 24109th+2.1%
May 25299th−2.7%
May 26349th−6.6%
May 27331st−3.9%
May 28310th−3%
May 29312th−3.2%
May 30265th−2.1%
May 31326th−3.7%
June 1159th+0.3%
June 2113th+1.9%
June 3133rd+1.1%
June 4143rd+0.8%
June 5158th+0.3%
June 6139th+1%
June 7160th+0.2%
June 8206th−1%
June 9185th−0.4%
June 10142nd+0.8%
June 11161st+0.2%
June 12146th+0.6%
June 13202nd−0.8%
June 14125th+1.4%
June 15188th−0.5%
June 16131st+1.2%
June 17136th+1.1%
June 18114th+1.9%
June 19156th+0.4%
June 2092nd+3.3%
June 21122nd+1.5%
June 22173rd0%
June 23138th+1%
June 24117th+1.8%
June 25105th+2.5%
June 26108th+2.2%
June 2771st+4.1%
June 2882nd+3.8%
June 29111th+2%
June 3087th+3.7%
July 127th+6.5%
July 230th+6.3%
July 3121st+1.5%
July 4363rd−21%
July 5348th−6.5%
July 696th+3.2%
July 76th+8.8%
July 818th+7.3%
July 940th+5.7%
July 1045th+5.4%
July 1135th+5.9%
July 1281st+3.9%
July 13154th+0.4%
July 1454th+4.9%
July 1543rd+5.6%
July 1641st+5.7%
July 1749th+5.3%
July 1838th+5.7%
July 1988th+3.7%
July 20103rd+2.7%
July 2159th+4.8%
July 2252nd+5%
July 2350th+5.1%
July 2468th+4.3%
July 2542nd+5.7%
July 2674th+4%
July 27104th+2.5%
July 2865th+4.3%
July 2970th+4.1%
July 3069th+4.2%
July 3190th+3.4%
August 137th+5.8%
August 275th+4%
August 3116th+1.8%
August 479th+3.9%
August 566th+4.3%
August 673rd+4.1%
August 772nd+4.1%
August 816th+7.3%
August 947th+5.3%
August 1093rd+3.2%
August 1167th+4.3%
August 1244th+5.5%
August 1398th+3%
August 1451st+5%
August 1521st+7.1%
August 1636th+5.9%
August 1786th+3.7%
August 1853rd+4.9%
August 1962nd+4.5%
August 2039th+5.7%
August 2161st+4.6%
August 2231st+6.2%
August 2360th+4.7%
August 2499th+2.9%
August 2576th+4%
August 2664th+4.4%
August 2746th+5.4%
August 2829th+6.5%
August 2920th+7.1%
August 3034th+6%
August 3184th+3.8%
September 1250th−1.8%
September 2222nd−1.2%
September 3178th−0.1%
September 4145th+0.8%
September 5102nd+2.7%
September 6124th+1.4%
September 7106th+2.4%
September 813th+7.7%
September 91st+10.5%
September 105th+9.1%
September 1191st+3.3%
September 123rd+9.8%
September 1333rd+6%
September 1424th+6.7%
September 158th+8.6%
September 169th+8.4%
September 174th+9.1%
September 1810th+8.3%
September 192nd+9.9%
September 207th+8.8%
September 2132nd+6.1%
September 2222nd+7.1%
September 2314th+7.6%
September 2417th+7.3%
September 2525th+6.6%
September 2612th+7.7%
September 2726th+6.5%
September 2885th+3.8%
September 2978th+3.9%
September 3095th+3.2%
October 148th+5.3%
October 277th+3.9%
October 357th+4.9%
October 494th+3.2%
October 5129th+1.3%
October 6115th+1.8%
October 7118th+1.7%
October 8119th+1.6%
October 9170th0%
October 1083rd+3.8%
October 11130th+1.2%
October 12213th−1.1%
October 13315th−3.3%
October 14165th+0.1%
October 15132nd+1.2%
October 16180th−0.2%
October 17123rd+1.5%
October 18164th+0.2%
October 19292nd−2.5%
October 20194th−0.6%
October 21197th−0.7%
October 22163rd+0.2%
October 23200th−0.8%
October 24128th+1.3%
October 25151st+0.5%
October 26252nd−1.8%
October 27205th−0.9%
October 28183rd−0.3%
October 29214th−1.1%
October 30305th−2.8%
October 31357th−10.4%
November 1112th+2%
November 2187th−0.5%
November 3172nd0%
November 4175th0%
November 5148th+0.5%
November 6186th−0.5%
November 7120th+1.6%
November 8155th+0.4%
November 9254th−1.8%
November 10204th−0.8%
November 11168th+0.1%
November 12189th−0.5%
November 13320th−3.5%
November 14140th+1%
November 15141st+0.9%
November 16208th−1%
November 17176th−0.1%
November 18157th+0.4%
November 19134th+1.1%
November 20100th+2.8%
November 2180th+3.9%
November 22337th−4.2%
November 23359th−11.2%
November 24356th−10%
November 25358th−10.6%
November 26355th−9.8%
November 27360th−12.7%
November 28354th−9.3%
November 29317th−3.3%
November 30289th−2.5%
December 1137th+1.1%
December 2152nd+0.4%
December 3167th+0.1%
December 4226th−1.4%
December 5171st0%
December 6234th−1.6%
December 7321st−3.5%
December 8273rd−2.2%
December 9293rd−2.5%
December 10240th−1.6%
December 11280th−2.2%
December 12101st+2.8%
December 13290th−2.5%
December 14239th−1.6%
December 15149th+0.5%
December 16110th+2%
December 1797th+3.1%
December 1856th+4.9%
December 1919th+7.2%
December 2011th+7.9%
December 2155th+4.9%
December 22107th+2.3%
December 23352nd−7.1%
December 24364th−27.5%
December 25366th−40.9%
December 26361st−14.3%
December 2758th+4.8%
December 2828th+6.5%
December 2915th+7.4%
December 3023rd+6.8%
December 31350th−6.6%

How was this calculated?

  • Data: 7,670 days of US births, 1994–2014, from FiveThirtyEight’s “births” dataset. It combines CDC/NCHS records for 1994–2003 and Social Security Administration records for 2004–2014.
  • No double counting: the two files overlap in 2000–2003, so those years come from the CDC/NCHS file only. Some sites use the SSA counts for those years instead. That gives September 9 about 12,344 births and swaps only 6th and 7th place in the top 10.
  • Averages: each date’s rank is its average births across the 21 years. February 29 is averaged over its 5 leap years and flagged.
  • Per 100,000: a date’s share of a year’s births. February 29 counts a quarter, since it comes once in four years.
  • License: the data is CC BY 4.0. Changes made: Combined the two files (1994-2003 CDC/NCHS, 2004-2014 SSA), so no year is counted twice. Averaged births per calendar date, with Feb 29 averaged over leap years only. Ranked the 366 dates.

Cite this page

InviteBird. "Most common birthdays: average US births by calendar date, 1994–2014." 2026. https://www.invitebird.com/tools/most-common-birthdays. Data: FiveThirtyEight, "births" (CDC/NCHS and SSA), CC BY 4.0.

Planning a birthday party?

Whatever the date, the party needs a guest list. Browse birthday invitations that collect RSVPs for you: design free, pay when you send, from $9.99.

A birthday table set for a party, with a layer cake, paper party hats, a few balloons and a stack of wrapped presents.
Digital illustration. A common birthday means more friends to share the party with; a rare one makes it easy to remember.

How do you add the birthday lookup to your site?

Paste this code into your page or blog post. The birthday lookup works inside your page, with no sign-up and no ads, and our Google Analytics and cookie banner are switched off inside it.

The InviteBird credit line under the birthday lookup is yours to keep or remove. The data line inside the lookup stays, because the CC BY 4.0 license requires it.

Common questions

How rare is my birthday?

Pick your date at the top of the page. You get its rank out of 366, the share of dates it beats, and how many of every 100,000 babies share it. The middle date, October 28, ranks 183rd with about 11,102 births on an average October 28.

Is a February 29 birthday really the rarest?

Yes. February 29 comes around only in leap years, so only about 64.3 in every 100,000 babies born in a year share it, about a quarter of an everyday date. In the leap years it exists, it sees about 10,462 births, close to an average day.

Is this data current?

It covers US births from 1994 to 2014, the years in the public dataset this page uses. It shows long-run patterns, not a single year. It covers the United States only.

Can I use the chart?

Yes. Download the PNG above or embed the lookup on your site. The data is CC BY 4.0, so keep the source line: FiveThirtyEight, from CDC/NCHS and SSA data.

Sources and further reading

The rankings, averages and chart are InviteBird’s own analysis of that public data. No InviteBird customer data is used.