Most Common Birthdays in the U.S.: Top Dates Ranked
Which birthdays appear most often, and why does September dominate the list? This guide ranks the leading dates, explains the statistics behind them and lets you check any birthday against all 366 calendar dates.
September 9 is the most common birthday in this U.S. dataset. It averaged about 12,344 births each time the date occurred from 1994 through 2014. Nine of the ten highest-ranked dates fall in September; July 7 is the only exception.
How Common Is Your Birthday?
Choose a month and day below. The checker compares your date with every calendar date using the same per-occurrence method as the ranked list. Therefore, February 29 is judged by the five times it actually occurred—not unfairly divided across all 21 years.
U.S. birthday frequency checker
How common is your birthday?
Select your birth month and day to compare it with all 366 calendar dates. Your birth year is not needed.
Per occurrence compares dates only when they actually happen. Across all years counts February 29 as rare because it appears only in leap years.
Historical U.S. birth records, 1994–2014. Rankings describe this dataset, not the probability of an individual birth today. Data: FiveThirtyEight (CDC/NCHS and SSA).
No birth year, account or personal details are required. The lookup runs from data stored inside the plugin.
Top 20 Most Common Birthdays
The table ranks birthdays by their average number of U.S. births each time the date occurred. In other words, rank #1 is the calendar date with the highest daily average across the study period.
| Rank | Birthday | Average births when date occurred | Month |
|---|---|---|---|
| 1 | September 9 | 12,344 | September |
| 2 | September 19 | 12,285 | September |
| 3 | September 12 | 12,282 | September |
| 4 | September 17 | 12,201 | September |
| 5 | September 10 | 12,190 | September |
| 6 | September 20 | 12,162 | September |
| 7 | July 7 | 12,147 | July |
| 8 | September 15 | 12,126 | September |
| 9 | September 16 | 12,114 | September |
| 10 | September 18 | 12,112 | September |
| 11 | December 20 | 12,064 | December |
| 12 | September 26 | 12,047 | September |
| 13 | September 8 | 12,029 | September |
| 14 | September 23 | 12,017 | September |
| 15 | August 8 | 12,006 | August |
| 16 | December 29 | 12,004 | December |
| 17 | December 19 | 11,998 | December |
| 18 | September 24 | 11,993 | September |
| 19 | July 8 | 11,980 | July |
| 20 | August 29 | 11,977 | August |
The difference at the top is fairly narrow. For example, only about 232 average births separate September 9 from September 18. Consequently, the table is better read as a cluster of high-frequency dates than as evidence that one date is overwhelmingly more likely than every other birthday.
What Is the Most Common Birth Month?
September has the highest average births per calendar-day occurrence in this dataset, at about 11,811. However, August has the largest total number of births because it has 31 days and accumulated roughly 7.62 million births across the covered years.
| Month | Average births per date occurrence | Total births in dataset | Daily-average rank |
|---|---|---|---|
| January | 10,721 | 6,979,322 | 12 |
| February | 10,981 | 6,511,697 | 8 |
| March | 10,979 | 7,147,368 | 9 |
| April | 10,874 | 6,850,733 | 11 |
| May | 11,022 | 7,175,367 | 6 |
| June | 11,306 | 7,122,586 | 4 |
| July | 11,563 | 7,527,284 | 3 |
| August | 11,712 | 7,624,626 | 2 |
| September | 11,811 | 7,440,659 | 1 |
| October | 11,204 | 7,293,822 | 5 |
| November | 10,927 | 6,884,173 | 10 |
| December | 10,991 | 7,155,101 | 7 |
Month totals should not be compared without considering month length. February naturally contains fewer calendar days, while 31-day months have more opportunities to accumulate births. For a fair date-level comparison, the daily average is more useful.
Why Are So Many Common Birthdays in September?
The data clearly shows a late-summer and September concentration, but the records alone cannot prove a single cause. Several overlapping factors may help explain the pattern.
Seasonal conception patterns
September births generally correspond to conceptions around December. Holidays, time off and seasonal behavior may contribute to that timing, although pregnancy length varies and conception dates cannot be inferred precisely from birthdays alone.
Weekday delivery patterns
Births are not distributed evenly across weekdays. Scheduled inductions and cesarean deliveries can reduce births on weekends and major holidays, while concentrating some deliveries on ordinary working days.
Holiday effects
Dates such as Christmas Day and New Year’s Day often show lower birth counts. This supports the idea that scheduling and hospital practice can influence the exact day of delivery, especially near holidays.
Long-term demographic change
The study combines 21 years. Population size, fertility rates and medical practice changed during that period, so each rank summarizes historical records rather than a fixed biological rule.
Therefore, a popular birthday does not reveal anything certain about an individual pregnancy. It simply means that the date recorded a relatively high average count within this specific U.S. dataset.
How We Calculated the Birthday Rankings
We combined daily U.S. birth counts from the CDC/NCHS for 1994–1999 with Social Security Administration records for 2000–2014. The source files overlap from 2000 through 2003, so those years were included only once. Altogether, the derived table contains 85,712,738 births across 7,670 days.
Primary ranking: average births per occurrence
For every month-and-day combination, we added its recorded births and divided by the number of times that date appeared. Ordinary dates appeared 21 times. February 29 appeared five times. Next, we sorted all 366 dates from the highest average to the lowest.
This method answers a direct question: When this date occurs, how many births happen on average? It also avoids automatically placing February 29 last merely because leap day is absent in most years.
Secondary view: average per calendar year
The checker also offers an “across all years” view. That version divides every date’s total by 21, including leap day. It answers a different question: How often does this birthday appear across a typical year in the full period? Because February 29 occurs only in leap years, its annualized result is much lower.
What Your Birthday Rank Means
A result of “#25 of 366” means 24 dates had a higher average in this dataset. It does not mean that exactly one in 25 people shares your birthday. Likewise, the percentile is a comparison among calendar dates, not a percentage of the population.
Rank
Rank #1 is the most common date; rank #366 is the least common under the selected method.
Average births
This is the mean number of recorded births when that date occurred—or per study year in annual mode.
Percentile
This compares the selected date with the other 365 possible birthdays in the same derived table.
Small gaps should not be overinterpreted. Neighboring ranks may differ by only a few births, and future data can change the order. If you want the other side of the distribution, explore our guide to the rarest birthdays in the U.S..
Are These the Most Common Birthdays in the World?
No. A credible worldwide birthday ranking would require comparable daily birth records from many countries for the same years. Registration systems, population sizes, holidays, seasons and healthcare practices differ, so a U.S. list should not be relabeled as a global list.
For the same reason, search phrases such as “most common birthdays in the UK,” “Australia” or “Canada” need country-specific official data. This page answers the U.S. question and clearly labels its geographic scope.
More Birthday Tools and Guides
Birthday frequency is one way to explore dates. You can also use the Random Birthday Generator to create fictional birthdays, discover birthday fun facts, find the weekday you were born or check zodiac signs by birthday.
Frequently Asked Questions
What is the number one most common birthday?
September 9 ranks #1 in the combined 1994–2014 U.S. records used here. It averaged approximately 12,344 births each time the date occurred.
What are the top three most common birthdays?
The top three are September 9, September 19 and September 12. Their respective averages are about 12,344, 12,285 and 12,282 births per occurrence.
Is September the most common birthday month?
Yes when comparing average births per calendar-day occurrence. September averages about 11,811 births per date occurrence. However, August has the largest total births in this dataset because it has 31 days.
Why are September birthdays so common?
Seasonal conception patterns may play a role. In addition, weekday scheduling, holiday effects and changing medical practices can influence exact delivery dates. The birth records show the pattern but do not prove one cause.
How can I find where my birthday ranks?
Use the birthday frequency checker near the top of this page. Select a month and day, then choose the per-occurrence view for the fairest comparison among all 366 dates.
Does my birth year change my birthday rank?
No. This ranking groups births by month and day across the full study period. Your personal birth year is not required, although birth patterns in an individual year may differ from the 21-year average.
Why can birthday rankings differ between websites?
Websites may use different years, countries or formulas. Some rank total births, while others use an average per date occurrence. Leap day treatment and overlapping source files can also change the result.
Will the most common birthday always stay the same?
Not necessarily. Newer birth records, demographic shifts and changes in delivery practices can alter the order. Treat this ranking as a transparent historical snapshot, not a permanent universal rule.
Sources and Editorial Notes
- CDC/NCHS daily U.S. birth data (1994–2003 mirror)
- Social Security Administration daily U.S. birth data (2000–2014 mirror)
- CDC National Vital Statistics System: Birth Data
- Source repository license and attribution information
Editorial approach: We label the geography and dates, distinguish totals from averages and avoid presenting associations as proven causes. The calculations can be reproduced from the linked files. This page may be updated when a comparable newer daily dataset becomes available.
