2000
#124,872
National surname rank
Recorded bearers 127
First available Census row
Per 100,000 0.05
Very Rare Last name
Trefny
A habitational surname referring to someone from the municipality of Trefní in the Czech Republic.
According to the 2020 US Census Bureau surname tables, roughly 133 Americans carry the last name Trefny. That puts it at #145,028 in the national surname ranking, appearing at a frequency of 0.04 per 100,000 people (about 1 in 2,577,100 residents).
This page is the full Name Census profile for the Trefny 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
133
1 in 2,577,100
Census rank
#145,028
2020 decennial data
Per 100,000
0.0
Frequency rate
Recorded bearers
116
very rare in the US
Popularity narrative
The Census Bureau recorded 116 bearers of the surname Trefny in its 2020 decennial surname file. At a rate of 0.04 per 100,000 residents, it holds the 145028th position in the national surname ranking.
Among Census respondents with the surname Trefny, the largest self-reported group is White at 90.5%. The next largest groups are Two or More Races (5.2%) and Black (2.6%).
Origin
Meaning and origin of Trefny
The surname TREFNY is of Czech origin and can be traced back to the 14th century. It is believed to have originated from the Czech word "tref", meaning "to hit" or "to strike". This suggests that the name may have been initially associated with someone who was skilled in hunting or archery.
In its earliest recorded forms, the surname was often spelled as "Trefny" or "Trefni". It is possible that these variations were used interchangeably in different regions of what is now the Czech Republic.
One of the earliest known records of the surname TREFNY can be found in a document from the city of Brno, dated 1387. This document mentions a certain Jan TREFNY, who was a landowner and prominent figure in the local community.
During the 15th and 16th centuries, the TREFNY surname began to spread across various parts of Bohemia and Moravia. Several villages and towns in these regions had families bearing this name, indicating that it had become well-established.
In the 17th century, a notable individual named Vaclav TREFNY (1595-1669) was a renowned poet and playwright who contributed significantly to the development of Czech literature during the Baroque period.
Another prominent figure was Frantisek TREFNY (1786-1845), a Czech author and educator who wrote several books on pedagogy and education reform. His works had a lasting impact on the educational system in Bohemia.
In the 19th century, Josef TREFNY (1832-1905) was a respected architect who designed numerous buildings in Prague and other cities across the Czech lands. Some of his most famous works include the Rudolfinum concert hall and the National Theatre in Prague.
Petr TREFNY (1903-1975) was a notable Czech historian and writer who specialized in the study of the Hussite movement and the Reformation in Bohemia. His books and research contributed significantly to the understanding of this important period in Czech history.
While the TREFNY surname may have originated in the Czech lands, over the centuries, it has also been found in other parts of Europe and beyond, as families migrated and settled in new regions.
Demographics
Ancestry and ethnicity for Trefny
Among Census respondents with the surname Trefny, the largest self-reported group is White at 90.5%. The next largest groups are Two or More Races (5.2%) and Black (2.6%).
The bar chart below shows how Trefny 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 Trefny surname at the time of the 2020 Census, not any inherent property of the name itself.
- White90.5% · 105
- Two or more races5.2% · 6
- Black or African American2.6% · 3
- Asian and Pacific Islander0.9% · 1
- American Indian and Alaska Native0.9% · 1
Timeline
Historical Census data for Trefny
Trefny 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
#126,018
National surname rank
Recorded bearers 136
+9 bearers (+7.1%)
Per 100,000 0.05
Rank movement Down 1,146 places
2020
#145,028
National surname rank
Recorded bearers 116
-20 bearers (-14.7%)
Per 100,000 0.04
Rank movement Down 19,010 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #124,872 | 127 | 0.05 | First available Census row | First available Census row |
| 2010 | #126,018 | 136 | 0.05 | +9 bearers (+7.1%) | Down 1,146 places |
| 2020 | #145,028 | 116 | 0.04 | -20 bearers (-14.7%) | Down 19,010 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 Trefny 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 | #126,018 | #145,028 | -15.1% |
| Count | 136 | 116 | -14.7% |
| Per 100K | 0.05 | 0.04 | -22.4% |
Between the 2010 and 2020 Census, the number of Trefny bearers went from 136 to 116 (-14.7% change). The surname moved down 19,010 positions in the national ranking, going from #126,018 to #145,028.
FAQ
Trefny surname: questions and answers
How many people in the U.S. have the surname Trefny?
Name Census estimates that about 133 living Americans carry the surname Trefny. Using the current population baseline, that works out to roughly 1 in 2,577,100 residents.
How common is Trefny?
Trefny ranks #145,028 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 116 people with the surname Trefny. That is different from the site's living-bearer estimate (133), 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 Trefny.
Has Trefny become more or less common over time?
Between 2010 and 2020, the surname Trefny went from 136 recorded bearers to 116. That is a decrease of 20 (-14.7%). In the national ranking it fell from #126,018 to #145,028.
What does the Census say about the background of Trefny?
Among Census respondents with the surname Trefny, the largest self-reported group is White at 90.5%. The next largest groups are Two or More Races (5.2%) and Black (2.6%). 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 Trefny in the 2020 Census, accounting for 90.5% (105 people in the source table).
What is the full ancestry breakdown?
Trefny appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (90.5%), Two or More Races (5.2%), Black (2.6%). 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 Trefny (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 Trefny mean?
A habitational surname referring to someone from the municipality of Trefní in the Czech Republic. 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 Trefny (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 surname Trefny?
HowManyOfMe.org, our sister site, answers that with the living-bearer count in one glance.