2000
#140,756
National surname rank
Recorded bearers 109
First available Census row
Per 100,000 0.04
Very Rare Last name
Piazzi
Italian surname denoting a person from Piazza Armerina in Sicily.
According to the 2020 US Census Bureau surname tables, roughly 134 Americans carry the last name Piazzi. That puts it at #144,270 in the national surname ranking, appearing at a frequency of 0.04 per 100,000 people (about 1 in 2,557,868 residents).
This page is the full Name Census profile for the Piazzi 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
134
1 in 2,557,868
Census rank
#144,270
2020 decennial data
Per 100,000
0.0
Frequency rate
Recorded bearers
117
very rare in the US
Popularity narrative
The Census Bureau recorded 117 bearers of the surname Piazzi in its 2020 decennial surname file. At a rate of 0.04 per 100,000 residents, it holds the 144270th position in the national surname ranking.
Among Census respondents with the surname Piazzi, the largest self-reported group is White at 97.4%. The next largest groups are Asian/Pacific Islander (1.7%) and Two or More Races (0.9%).
Origin
Meaning and origin of Piazzi
The surname Piazzi is of Italian origin and can be traced back to the 14th century. It is believed to have originated in the Piedmont region of northwestern Italy, specifically in the area around the city of Turin. The name is derived from the Italian word "piazza," meaning "square" or "marketplace," suggesting that it may have originated as a nickname for someone who lived near a town square or worked in a marketplace.
One of the earliest recorded instances of the name Piazzi can be found in the "Codice Diplomatico della Repubblica di Genova," a collection of documents from the Republic of Genoa dating back to the 13th century. In this collection, a person named "Guillelmus de Placia" is mentioned, which is likely an early variation of the name Piazzi.
During the Renaissance period, the Piazzi family was well-established in the city of Turin. Notable members of the family include Giovan Battista Piazzi (1746-1826), an Italian Catholic priest, mathematician, and astronomer best known for discovering the first asteroid, Ceres, in 1801. Another famous bearer of the name was Filippo Piazzi (1530-1604), an Italian painter and architect who worked extensively in Turin and Piedmont.
In the 17th century, the name Piazzi can be found in various records from the city of Genoa, such as birth and marriage registers. One notable individual from this period was Gerolamo Piazzi (1600-1668), a Genoese merchant and banker who was involved in the city's maritime trade.
Moving into the 18th and 19th centuries, the Piazzi surname continued to be associated with individuals from the Piedmont region, particularly in the areas around Turin and Genoa. Some notable figures include:
1. Giuseppe Piazzi (1786-1865), an Italian mathematician and astronomer who worked at the University of Palermo and made significant contributions to celestial mechanics.
2. Vincenzo Piazzi (1804-1867), an Italian painter and lithographer known for his landscapes and portraits.
3. Carlo Piazzi (1809-1888), an Italian architect and engineer who designed several buildings in Turin, including the Palazzo dell'Accademia delle Scienze.
4. Giulio Piazzi (1831-1902), an Italian journalist and writer who founded the newspaper "La Gazzetta del Popolo" in Turin.
5. Emilio Piazzi (1858-1938), an Italian politician and lawyer who served as a deputy in the Italian Parliament and was involved in the Risorgimento movement.
While the surname Piazzi has its roots in the Piedmont region of Italy, it has since spread to other parts of the country and beyond, carried by individuals and families who migrated over the centuries.
Demographics
Ancestry and ethnicity for Piazzi
Among Census respondents with the surname Piazzi, the largest self-reported group is White at 97.4%. The next largest groups are Asian/Pacific Islander (1.7%) and Two or More Races (0.9%).
The bar chart below shows how Piazzi 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 Piazzi surname at the time of the 2020 Census, not any inherent property of the name itself.
- White97.4% · 114
- Asian and Pacific Islander1.7% · 2
- Two or more races0.9% · 1
Timeline
Historical Census data for Piazzi
Piazzi 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
#146,201
National surname rank
Recorded bearers 113
+4 bearers (+3.7%)
Per 100,000 0.04
Rank movement Down 5,445 places
2020
#144,270
National surname rank
Recorded bearers 117
+4 bearers (+3.5%)
Per 100,000 0.04
Rank movement Up 1,931 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #140,756 | 109 | 0.04 | First available Census row | First available Census row |
| 2010 | #146,201 | 113 | 0.04 | +4 bearers (+3.7%) | Down 5,445 places |
| 2020 | #144,270 | 117 | 0.04 | +4 bearers (+3.5%) | Up 1,931 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 Piazzi 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 | #146,201 | #144,270 | 1.3% |
| Count | 113 | 117 | 3.5% |
| Per 100K | 0.04 | 0.04 | -2.1% |
Between the 2010 and 2020 Census, the number of Piazzi bearers went from 113 to 117 (+3.5% change). The surname moved up 1,931 positions in the national ranking, going from #146,201 to #144,270.
FAQ
Piazzi surname: questions and answers
How many people in the U.S. have the surname Piazzi?
Name Census estimates that about 134 living Americans carry the surname Piazzi. Using the current population baseline, that works out to roughly 1 in 2,557,868 residents.
How common is Piazzi?
Piazzi ranks #144,270 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 117 people with the surname Piazzi. That is different from the site's living-bearer estimate (134), 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 Piazzi.
Has Piazzi become more or less common over time?
Between 2010 and 2020, the surname Piazzi went from 113 recorded bearers to 117. That is an increase of 4 (+3.5%). In the national ranking it rose from #146,201 to #144,270.
What does the Census say about the background of Piazzi?
Among Census respondents with the surname Piazzi, the largest self-reported group is White at 97.4%. The next largest groups are Asian/Pacific Islander (1.7%) and Two or More Races (0.9%). 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 Piazzi in the 2020 Census, accounting for 97.4% (114 people in the source table).
What is the full ancestry breakdown?
Piazzi appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (97.4%), Asian/Pacific Islander (1.7%), Two or More Races (0.9%). 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 Piazzi (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 Piazzi mean?
Italian surname denoting a person from Piazza Armerina in Sicily. 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 Piazzi (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 Piazzi?
Find out how common the surname Piazzi is on our sister site HowManyOfMe.org — a quick modern estimate with the living-bearer count front and centre.