Jill Hennessy
There are approximately 5 people named Jill Hennessy living in the United States today. That makes this name combination very rare, occurring at a rate of about 1 in 68,550,868 Americans.
This estimate combines SSA birth records for the first name Jill with Census Bureau frequency data for the surname Hennessy. Below you will find a breakdown of both names, including popularity trends, gender data, and ancestry information.
Expected bearers
5
1 in 68,550,868
Named Jill
170K
Alive today
Named Hennessy
11K
Alive today
US population
343M
Denominator
Estimated living: 170K
Rarity: Common
Gender: Female
Peak year: 1966
Average age: 57
Estimated bearers: 11K
Rarity: Uncommon
Census rank: #3,790
Per 100K: 3.17
Top ancestry: White (94.7%)
First name trend
Jill: popularity over time
Year-by-year SSA birth registrations for the first name Jill. The peak year was 1966 with 7,885 births. The average person named Jill today is 57 years old.
Babies born per year
Ethnicity
Ancestry of the Hennessy surname
Self-reported race and ethnicity breakdown for people with the surname Hennessy, from the 2010 US Census Bureau. The largest group is White at 94.7%.
- White94.7%
- Hispanic or Latino2.1%
- Two or more races1.4%
- Asian and Pacific Islander0.9%
- Black or African American0.6%
- American Indian and Alaska Native0.2%
Methodology
How we calculated this
The first name Jill has a living-bearer frequency of 0.0497% of the US population, based on 170,298 estimated living Americans carrying this first name (from SSA birth records going back to 1880, adjusted for mortality using CDC life tables).
The surname Hennessy appears at a rate of 3.17 per 100,000 residents in the 2010 Census Bureau surname file, which translates to a frequency of 0.0032%.
Multiplying these two independent frequencies against the current US population of 342,754,338 gives an expected count of approximately 5 people with the full name Jill Hennessy. This assumes statistical independence between first and last names, which is a simplification but produces reasonable estimates for most combinations.
Related
Other people named Jill
FAQ
Jill Hennessy: questions and answers
How many people are named Jill Hennessy?
We estimate approximately 5 people in the United States share the full name Jill Hennessy. That works out to about 1 in 68,550,868 Americans. This is calculated by combining the first-name frequency (0.0497%) with the surname frequency (3.17 per 100K) against the current US population.
How rare is the name Jill Hennessy?
We classify Jill Hennessy as "Very Rare". About 1 in 68,550,868 Americans share this exact first and last name combination.
Is Jill a male or female name?
Jill is predominantly female. Out of 208,553 total SSA registrations, 0.2% were male and 99.8% were female. See the full Jill 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.