2000
#129,619
National surname rank
Recorded bearers 121
First available Census row
Per 100,000 0.04
Very Rare Last name
Dithomas
A surname derived from the Welsh personal name "Thomas" with the honorific prefix "Di-".
According to the 2020 US Census Bureau surname tables, roughly 122 Americans carry the last name Dithomas. That puts it at #152,339 in the national surname ranking, appearing at a frequency of 0.04 per 100,000 people (about 1 in 2,809,462 residents).
This page is the full Name Census profile for the Dithomas 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
122
1 in 2,809,462
Census rank
#152,339
2020 decennial data
Per 100,000
0.0
Frequency rate
Recorded bearers
106
very rare in the US
Popularity narrative
The Census Bureau recorded 106 bearers of the surname Dithomas in its 2020 decennial surname file. At a rate of 0.04 per 100,000 residents, it holds the 152339th position in the national surname ranking.
Among Census respondents with the surname Dithomas, the largest self-reported group is White at 92.5%. The next largest groups are Hispanic (4.7%) and Two or More Races (1.9%).
Origin
Meaning and origin of Dithomas
The surname DITHOMAS is of Welsh origin, with its roots traced back to the medieval period. The name is derived from the Welsh words "di" meaning "without" and "thomas" which is a personal name. It is believed that the surname was originally given as a descriptive name to distinguish someone who was not named Thomas.
One of the earliest recorded instances of the DITHOMAS surname can be found in the Herefordshire Subsidy Rolls of 1327, where a Phillip Dithomas is mentioned. This suggests that the name was already established in the Welsh Marches region during the 14th century.
In the 16th century, a reference to a Richard Dithomas appears in the records of the Court of the Marches of Wales, held in Ludlow Castle. This indicates that the name had spread to the neighboring English counties bordering Wales.
The DITHOMAS surname is also found in early parish records from various parts of Wales, such as Pembrokeshire and Glamorgan. In the 17th century, a notable individual named John Dithomas (1608-1677) was a Welsh clergyman and author from Carmarthenshire.
Another prominent figure with this surname was Sir William Dithomas (1718-1801), a Welsh landowner and Member of Parliament for Radnorshire. He inherited the Llanfair Clydogau estate in Cardiganshire, which had been in the family since the 16th century.
During the 18th century, the DITHOMAS surname also appears in records from Montgomeryshire, with a family of that name residing in the village of Berriew. One member, David Dithomas (1761-1832), was a renowned Welsh poet and writer.
While the DITHOMAS surname is still found predominantly in Wales, it has also spread to other parts of the United Kingdom and beyond due to migration and diaspora. However, its origins and early history are firmly rooted in the Welsh language and culture.
Demographics
Ancestry and ethnicity for Dithomas
Among Census respondents with the surname Dithomas, the largest self-reported group is White at 92.5%. The next largest groups are Hispanic (4.7%) and Two or More Races (1.9%).
The bar chart below shows how Dithomas 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 Dithomas surname at the time of the 2020 Census, not any inherent property of the name itself.
- White92.5% · 98
- Hispanic or Latino4.7% · 5
- Two or more races1.9% · 2
- Asian and Pacific Islander0.9% · 1
Timeline
Historical Census data for Dithomas
Dithomas 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
#147,253
National surname rank
Recorded bearers 112
-9 bearers (-7.4%)
Per 100,000 0.04
Rank movement Down 17,634 places
2020
#152,339
National surname rank
Recorded bearers 106
-6 bearers (-5.4%)
Per 100,000 0.04
Rank movement Down 5,086 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #129,619 | 121 | 0.04 | First available Census row | First available Census row |
| 2010 | #147,253 | 112 | 0.04 | -9 bearers (-7.4%) | Down 17,634 places |
| 2020 | #152,339 | 106 | 0.04 | -6 bearers (-5.4%) | Down 5,086 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 Dithomas 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 | #147,253 | #152,339 | -3.5% |
| Count | 112 | 106 | -5.4% |
| Per 100K | 0.04 | 0.04 | -11.3% |
Between the 2010 and 2020 Census, the number of Dithomas bearers went from 112 to 106 (-5.4% change). The surname moved down 5,086 positions in the national ranking, going from #147,253 to #152,339.
FAQ
Dithomas surname: questions and answers
How many people in the U.S. have the surname Dithomas?
Name Census estimates that about 122 living Americans carry the surname Dithomas. Using the current population baseline, that works out to roughly 1 in 2,809,462 residents.
How common is Dithomas?
Dithomas ranks #152,339 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 106 people with the surname Dithomas. That is different from the site's living-bearer estimate (122), 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 Dithomas.
Has Dithomas become more or less common over time?
Between 2010 and 2020, the surname Dithomas went from 112 recorded bearers to 106. That is a decrease of 6 (-5.4%). In the national ranking it fell from #147,253 to #152,339.
What does the Census say about the background of Dithomas?
Among Census respondents with the surname Dithomas, the largest self-reported group is White at 92.5%. The next largest groups are Hispanic (4.7%) and Two or More Races (1.9%). 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 Dithomas in the 2020 Census, accounting for 92.5% (98 people in the source table).
What is the full ancestry breakdown?
Dithomas appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (92.5%), Hispanic (4.7%), Two or More Races (1.9%). 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 Dithomas (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 Dithomas mean?
A surname derived from the Welsh personal name "Thomas" with the honorific prefix "Di-". 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 Dithomas (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 are called Dithomas?
For a quick modern take, check how many Americans have the surname Dithomas on our sister site HowManyOfMe.org.