2000
#135,837
National surname rank
Recorded bearers 114
First available Census row
Per 100,000 0.04
Very Rare Last name
Thomasen
A patronymic surname meaning "son of Thomas".
According to the 2020 US Census Bureau surname tables, roughly 124 Americans carry the last name Thomasen. That puts it at #150,935 in the national surname ranking, appearing at a frequency of 0.04 per 100,000 people (about 1 in 2,764,148 residents).
This page is the full Name Census profile for the Thomasen surname. You will find the Census Bureau frequency data, a multi-census history view, an ancestry and ethnicity breakdown based on self-reported demographics, the name's meaning and origin where available, and answers to the most common questions people ask about this surname.
Bearers in the US
124
1 in 2,764,148
Census rank
#150,935
2020 decennial data
Per 100,000
0.0
Frequency rate
Recorded bearers
108
very rare in the US
Popularity narrative
The Census Bureau recorded 108 bearers of the surname Thomasen in its 2020 decennial surname file. At a rate of 0.04 per 100,000 residents, it holds the 150935th position in the national surname ranking.
Among Census respondents with the surname Thomasen, the largest self-reported group is White at 92.6%. The next largest groups are Asian/Pacific Islander (2.8%) and Two or More Races (2.8%).
Origin
Meaning and origin of Thomasen
The surname Thomasen is of Danish origin and can be traced back to the 16th century. It is a patronymic name, derived from the given name Thomas, which means "twin" in Aramaic. The suffix "-sen" is a common Danish and Scandinavian patronymic suffix, indicating "son of."
One of the earliest known records of the name Thomasen can be found in the Danish Census of 1645, where it appears as "Thomassen." This spelling variation was commonly used in the past, and the name likely evolved from "Thomassen" to "Thomasen" over time.
The name Thomasen has been associated with various regions in Denmark, including Jutland, Funen, and Zealand. It was particularly prevalent in the coastal areas, where many families bore the name due to their involvement in fishing and maritime activities.
In the late 16th century, a notable figure named Hans Thomasen (1532-1610) was a Danish Protestant theologian and Lutheran reformer. He played a significant role in the establishment of the Lutheran Church in Denmark and authored several influential works on theology.
Another prominent individual with the surname was Jens Thomasen (1619-1677), a Danish naval officer and admiral. He served in the Danish Navy during the Dano-Swedish War of 1658-1660 and was known for his bravery and strategic leadership in several naval battles.
In the 19th century, Niels Thomasen (1821-1892) was a Danish businessman and industrialist who founded the Thomasen Brewery in Copenhagen. The brewery became one of the largest and most successful in Denmark, and its beer was widely exported.
The name Thomasen has also been associated with various place names in Denmark, such as Thomasen's Farm (Thomasens Gård) in Jutland and Thomasen's Village (Thomasensby) in Zealand. These place names likely originated from families or individuals bearing the surname Thomasen who settled in those areas.
Towards the end of the 19th century, a notable figure named Carl Thomasen (1862-1942) was a Danish artist and painter. He was known for his landscapes and seascapes, and his works are exhibited in several art museums in Denmark and abroad.
Demographics
Ancestry and ethnicity for Thomasen
Among Census respondents with the surname Thomasen, the largest self-reported group is White at 92.6%. The next largest groups are Asian/Pacific Islander (2.8%) and Two or More Races (2.8%).
The bar chart below shows how Thomasen bearers described their own race and ethnicity on the 2020 Census form. The Census Bureau groups responses into six broad categories: White, Black or African American, Hispanic or Latino, Asian and Pacific Islander, American Indian and Alaska Native, and Two or More Races. When a category has too few respondents for a given surname, the Bureau suppresses the figure to protect individual privacy, which is why some names show fewer than six slices.
Percentages are shown for every Census year so the breakdown stays comparable over time. When the source file also includes raw headcounts, Name Census shows those alongside the percentages in the legend.
Keep in mind that these are self-reported numbers. A person's surname does not determine their race or ethnicity, and the distribution you see here reflects the specific population who happened to carry the Thomasen surname at the time of the 2020 Census, not any inherent property of the name itself.
- White92.6% · 100
- Asian and Pacific Islander2.8% · 3
- Two or more races2.8% · 3
- Hispanic or Latino1.9% · 2
Timeline
Historical Census data for Thomasen
Thomasen appears in 3 published Census surname files: 2000, 2010, 2020. The cards below show how the name's rank and bearer count changed across each release.
2010
#150,452
National surname rank
Recorded bearers 109
-5 bearers (-4.4%)
Per 100,000 0.04
Rank movement Down 14,615 places
2020
#150,935
National surname rank
Recorded bearers 108
-1 bearers (-0.9%)
Per 100,000 0.04
Rank movement Down 483 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #135,837 | 114 | 0.04 | First available Census row | First available Census row |
| 2010 | #150,452 | 109 | 0.04 | -5 bearers (-4.4%) | Down 14,615 places |
| 2020 | #150,935 | 108 | 0.04 | -1 bearers (-0.9%) | Down 483 places |
For 2020, the Census Bureau published race and Hispanic-origin columns as counts rather than percentages. Name Census converts those counts back into shares so the ancestry section stays comparable with the older surname files.
Year on year
2010 vs 2020 Census
How has the Thomasen surname changed between Census years? The chart shows bearer count side by side, and the table compares rank, count, and frequency.
Census year comparison
20102020
| Metric | 2010 | 2020 | Change |
|---|---|---|---|
| Rank | #150,452 | #150,935 | -0.3% |
| Count | 109 | 108 | -0.9% |
| Per 100K | 0.04 | 0.04 | -9.7% |
Between the 2010 and 2020 Census, the number of Thomasen bearers went from 109 to 108 (-0.9% change). The surname moved down 483 positions in the national ranking, going from #150,452 to #150,935.
FAQ
Thomasen surname: questions and answers
How many people in the U.S. have the surname Thomasen?
Name Census estimates that about 124 living Americans carry the surname Thomasen. Using the current population baseline, that works out to roughly 1 in 2,764,148 residents.
How common is Thomasen?
Thomasen ranks #150,935 in the 2020 Census surname tables and is classified on this site as "Very Rare." The Census recorded the name at a frequency of 0.04 per 100,000 residents, which is about 0 people out of every 100,000.
How many people with this surname were counted in the Census?
The raw 2020 Census file counted 108 people with the surname Thomasen. That is different from the site's living-bearer estimate (124), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 0.04 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 0.04 per 100,000 means that if you picked a random group of 100,000 U.S. residents, you would expect about 0 of them to have the surname Thomasen.
Has Thomasen become more or less common over time?
Between 2010 and 2020, the surname Thomasen went from 109 recorded bearers to 108. That is a decrease of 1 (-0.9%). In the national ranking it fell from #150,452 to #150,935.
What does the Census say about the background of Thomasen?
Among Census respondents with the surname Thomasen, the largest self-reported group is White at 92.6%. The next largest groups are Asian/Pacific Islander (2.8%) and Two or More Races (2.8%). These figures come from the 2020 Census Bureau surname tables, based on how respondents described their own race and ethnicity.
Which group reports this surname most often?
White is the largest self-reported group for the surname Thomasen in the 2020 Census, accounting for 92.6% (100 people in the source table).
What is the full ancestry breakdown?
Thomasen appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (92.6%), Asian/Pacific Islander (2.8%), Two or More Races (2.8%). For 2020, the source file also published raw headcounts for each group, which is why this page can show both percentages and counts in the ancestry section.
Is this page using the latest Census data?
Yes. This page is using the latest surname file currently loaded on Name Census, which is 2020. The historical section above also keeps any older Census surname entries we have for Thomasen (2000, 2010, 2020).
Does the Census include every surname?
No. The Census Bureau only publishes surnames that appeared at least 100 times in a given decennial Census. That means very rare surnames are excluded entirely, and a surname can appear in one Census release but disappear from a later one if it falls below the reporting threshold.
Why don't the ancestry percentages always add up to exactly 100%?
There are two main reasons: rounding and suppression. The Census Bureau rounds published values, and it may suppress very small cells to protect privacy. For 2020, the Bureau also published raw group counts rather than direct percentages, so Name Census converts those counts back into shares for comparability across census years.
What does Thomasen mean?
A patronymic surname meaning "son of Thomas". The fuller origin note on this page goes into more detail.
Where does the surname data come from?
All surname statistics on Name Census are drawn from the US Census Bureau's decennial surname frequency tables. These files list every surname that appeared 100 or more times in the 2020 Census, along with a count, a per-100,000 rate, and a self-reported demographic breakdown. You can read the full explanation on our methodology page.
How does Name Census estimate living bearers?
For surnames, Name Census does not age cohorts the way it does for first names. Instead, it takes the Census Bureau's published frequency for Thomasen (0.04 per 100,000) and applies that rate to the current U.S. resident population to estimate how many living Americans have the surname today.
How many people have the last name Thomasen?
See how many people have the last name Thomasen on HowManyOfMe.org, our sister site built around that single question.