William Petersen
There are approximately 463 people named William Petersen living in the United States today. That makes this name combination very rare, occurring at a rate of about 1 in 740,290 Americans.
This estimate combines SSA birth records for the first name William with Census Bureau frequency data for the surname Petersen. Below you will find a breakdown of both names, including popularity trends, gender data, and ancestry information.
Expected bearers
463
1 in 740,290
Named William
2.3M
Alive today
Named Petersen
68K
Alive today
US population
343M
Denominator
Estimated living: 2.3M
Rarity: Very Common
Gender: Male
Peak year: 1947
Average age: 54
Estimated bearers: 68K
Rarity: Uncommon
Census rank: #571
Per 100K: 19.83
Top ancestry: White (93.4%)
First name trend
William: popularity over time
Year-by-year SSA birth registrations for the first name William. The peak year was 1947 with 67,155 births. The average person named William today is 54 years old.
Babies born per year
Ethnicity
Ancestry of the Petersen surname
Self-reported race and ethnicity breakdown for people with the surname Petersen, from the 2010 US Census Bureau. The largest group is White at 93.4%.
- White93.4%
- Hispanic or Latino2.5%
- Two or more races1.6%
- Black or African American1.3%
- Asian and Pacific Islander0.8%
- American Indian and Alaska Native0.4%
Methodology
How we calculated this
The first name William has a living-bearer frequency of 0.6813% of the US population, based on 2,335,115 estimated living Americans carrying this first name (from SSA birth records going back to 1880, adjusted for mortality using CDC life tables).
The surname Petersen appears at a rate of 19.83 per 100,000 residents in the 2010 Census Bureau surname file, which translates to a frequency of 0.0198%.
Multiplying these two independent frequencies against the current US population of 342,754,338 gives an expected count of approximately 463 people with the full name William Petersen. This assumes statistical independence between first and last names, which is a simplification but produces reasonable estimates for most combinations.
Related
Other people named William
Related
Other people with the surname Petersen
FAQ
William Petersen: questions and answers
How many people are named William Petersen?
We estimate approximately 463 people in the United States share the full name William Petersen. That works out to about 1 in 740,290 Americans. This is calculated by combining the first-name frequency (0.6813%) with the surname frequency (19.83 per 100K) against the current US population.
How rare is the name William Petersen?
We classify William Petersen as "Very Rare". About 1 in 740,290 Americans share this exact first and last name combination.
Is William a male or female name?
William is predominantly male. Out of 4,205,026 total SSA registrations, 99.6% were male and 0.4% were female. See the full William profile for detailed gender data.
Where does this data come from?
First-name data comes from the Social Security Administration's national baby name files (1880 to 2024). Surname data comes from the 2010 US Census Bureau decennial surname tables. Living-bearer estimates use CDC actuarial life tables to adjust for mortality. Read the full methodology.