2000
#32,743
National surname rank
Recorded bearers 661
First available Census row
Per 100,000 0.25
Rare Last name
Si
A surname indicating geographic origin or residency in a particular place.
According to the 2020 US Census Bureau surname tables, roughly 2,026 Americans carry the last name Si. That puts it at #15,873 in the national surname ranking, appearing at a frequency of 0.59 per 100,000 people (about 1 in 169,178 residents).
This page is the full Name Census profile for the Si 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.
For British records, Name Census UK has a British surname profile for Si with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
2.0K
1 in 169,178
Census rank
#15,873
2020 decennial data
Per 100,000
0.6
Frequency rate
Recorded bearers
1.8K
rare in the US
Popularity narrative
The Census Bureau recorded 1,767 bearers of the surname Si in its 2020 decennial surname file. At a rate of 0.59 per 100,000 residents, it holds the 15873rd position in the national surname ranking.
Among Census respondents with the surname Si, the largest self-reported group is Asian/Pacific Islander at 86.4%. The next largest groups are White (6.4%) and Hispanic (4.0%).
Origin
Meaning and origin of Si
The surname "Si" is believed to have originated in China, where it is a relatively common surname dating back to ancient times. It is thought to have derived from the Chinese character "思," which means "to think" or "to consider."
One of the earliest known references to the surname "Si" can be found in the historical records of the Song Dynasty (960-1279 CE). During this period, the name was particularly prevalent in the provinces of Zhejiang and Jiangsu, which were centers of culture and scholarship.
In the Ming Dynasty (1368-1644 CE), several notable individuals bearing the surname "Si" emerged. One of the most prominent was Si Ku, a scholar and philosopher who lived during the 15th century. His works on Confucian thought and ethics were highly influential in his time.
Another notable figure from this era was Si Shen, a renowned painter and calligrapher who lived in the late 16th century. His works are highly regarded and can be found in museums and collections around the world.
During the Qing Dynasty (1644-1912 CE), the surname "Si" continued to be associated with scholars and intellectuals. One notable example was Si Maqian, a historian and writer who lived in the 18th century. His works provided valuable insights into the history and culture of China during the Qing era.
In more recent times, the surname "Si" has been carried by several influential individuals, including Si Zheng, a prominent economist and politician who played a key role in shaping China's economic policies in the late 20th century.
Another well-known bearer of the surname "Si" is Si Tu, an acclaimed artist and sculptor who has gained international recognition for his work. His sculptures can be found in major cities around the world, including New York and London.
While the surname "Si" is most commonly associated with China, it has also been found in other parts of Asia, including Vietnam and Korea. However, the origins and historical significance of the name in these regions are less well-documented.
Demographics
Ancestry and ethnicity for Si
Among Census respondents with the surname Si, the largest self-reported group is Asian/Pacific Islander at 86.4%. The next largest groups are White (6.4%) and Hispanic (4.0%).
The bar chart below shows how Si 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 Si surname at the time of the 2020 Census, not any inherent property of the name itself.
- Asian and Pacific Islander86.4% · 1,526
- White6.4% · 113
- Hispanic or Latino4.0% · 70
- Black or African American1.9% · 34
- Two or more races1.2% · 21
- American Indian and Alaska Native0.2% · 3
Timeline
Historical Census data for Si
Si 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
#22,158
National surname rank
Recorded bearers 1,166
+505 bearers (+76.4%)
Per 100,000 0.40
Rank movement Up 10,585 places
2020
#15,873
National surname rank
Recorded bearers 1,767
+601 bearers (+51.5%)
Per 100,000 0.59
Rank movement Up 6,285 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #32,743 | 661 | 0.25 | First available Census row | First available Census row |
| 2010 | #22,158 | 1,166 | 0.40 | +505 bearers (+76.4%) | Up 10,585 places |
| 2020 | #15,873 | 1,767 | 0.59 | +601 bearers (+51.5%) | Up 6,285 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 Si 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 | #22,158 | #15,873 | 28.4% |
| Count | 1,166 | 1,767 | 51.5% |
| Per 100K | 0.40 | 0.59 | 47.8% |
Between the 2010 and 2020 Census, the number of Si bearers went from 1,166 to 1,767 (+51.5% change). The surname moved up 6,285 positions in the national ranking, going from #22,158 to #15,873.
FAQ
Si surname: questions and answers
How many people in the U.S. have the surname Si?
Name Census estimates that about 2,026 living Americans carry the surname Si. Using the current population baseline, that works out to roughly 1 in 169,178 residents.
How common is Si?
Si ranks #15,873 in the 2020 Census surname tables and is classified on this site as "Rare." The Census recorded the name at a frequency of 0.59 per 100,000 residents, which is about 1 people out of every 100,000.
How many people with this surname were counted in the Census?
The raw 2020 Census file counted 1,767 people with the surname Si. That is different from the site's living-bearer estimate (2,026), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 0.59 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 0.59 per 100,000 means that if you picked a random group of 100,000 U.S. residents, you would expect about 1 of them to have the surname Si.
Has Si become more or less common over time?
Between 2010 and 2020, the surname Si went from 1,166 recorded bearers to 1,767. That is an increase of 601 (+51.5%). In the national ranking it rose from #22,158 to #15,873.
What does the Census say about the background of Si?
Among Census respondents with the surname Si, the largest self-reported group is Asian/Pacific Islander at 86.4%. The next largest groups are White (6.4%) and Hispanic (4.0%). 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?
Asian/Pacific Islander is the largest self-reported group for the surname Si in the 2020 Census, accounting for 86.4% (1,526 people in the source table).
What is the full ancestry breakdown?
Si appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are Asian/Pacific Islander (86.4%), White (6.4%), Hispanic (4.0%). 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 Si (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 Si mean?
A surname indicating geographic origin or residency in a particular place. 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 Si (0.59 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 share the surname Si?
For a faster, more casual read, check HowManyOfMe.org — our sister site built around that single question.