2000
#143,847
National surname rank
Recorded bearers 106
First available Census row
Per 100,000 0.04
Very Rare Last name
Iwase
A Japanese surname signifying someone residing near or descended from a rocky shore.
According to the 2020 US Census Bureau surname tables, roughly 125 Americans carry the last name Iwase. That puts it at #150,205 in the national surname ranking, appearing at a frequency of 0.04 per 100,000 people (about 1 in 2,742,035 residents).
This page is the full Name Census profile for the Iwase 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
125
1 in 2,742,035
Census rank
#150,205
2020 decennial data
Per 100,000
0.0
Frequency rate
Recorded bearers
109
very rare in the US
Popularity narrative
The Census Bureau recorded 109 bearers of the surname Iwase in its 2020 decennial surname file. At a rate of 0.04 per 100,000 residents, it holds the 150205th position in the national surname ranking.
Among Census respondents with the surname Iwase, the largest self-reported group is Asian/Pacific Islander at 98.2%. The next largest groups are White (0.9%) and Two or More Races (0.9%).
Origin
Meaning and origin of Iwase
The surname Iwase is of Japanese origin, with its roots tracing back to the late 16th century. It is believed to have emerged from the Iwase district of present-day Kyoto Prefecture, where the name was likely derived from the Japanese words "iwa," meaning rock, and "se," referring to a narrow pathway or gorge.
One of the earliest recorded instances of the Iwase name can be found in the Edo period (1603-1868) records of the Iwase village, which was situated in the mountainous region of Kyoto. During this time, the name was also documented in several local manuscripts and registries, often associated with landowners and prominent families in the area.
In the 17th century, a notable figure named Iwase Hisanori (1627-1704) gained recognition as a skilled samurai and loyal retainer of the Tokugawa shogunate. His descendants continued to carry the Iwase name, contributing to its spread across various regions of Japan.
Another prominent individual bearing the Iwase surname was Iwase Yoshiyuki (1819-1887), a scholar and educator who played a pivotal role in the modernization of Japan's education system during the Meiji Restoration period. His works on educational reform and Western ideologies had a significant impact on the country's intellectual landscape.
In the early 20th century, Iwase Masao (1901-1974) gained recognition as a pioneering artist and printmaker. His woodblock prints, featuring traditional Japanese themes and landscapes, earned him international acclaim and are now part of prestigious museum collections worldwide.
Throughout the years, the Iwase name has also been associated with various other notable individuals, such as Iwase Tatsuo (1905-1967), a renowned architect known for his innovative designs, and Iwase Kiyoko (1920-1998), a celebrated writer and literary critic who contributed significantly to the promotion of women's literature in Japan.
While the Iwase surname may have originated from a specific geographical location, it has since spread across Japan and, to a lesser extent, other parts of the world, carried by individuals and families with diverse backgrounds and accomplishments.
Demographics
Ancestry and ethnicity for Iwase
Among Census respondents with the surname Iwase, the largest self-reported group is Asian/Pacific Islander at 98.2%. The next largest groups are White (0.9%) and Two or More Races (0.9%).
The bar chart below shows how Iwase 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 Iwase surname at the time of the 2020 Census, not any inherent property of the name itself.
- Asian and Pacific Islander98.2% · 107
- White0.9% · 1
- Two or more races0.9% · 1
Timeline
Historical Census data for Iwase
Iwase 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
#116,829
National surname rank
Recorded bearers 149
+43 bearers (+40.6%)
Per 100,000 0.05
Rank movement Up 27,018 places
2020
#150,205
National surname rank
Recorded bearers 109
-40 bearers (-26.8%)
Per 100,000 0.04
Rank movement Down 33,376 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #143,847 | 106 | 0.04 | First available Census row | First available Census row |
| 2010 | #116,829 | 149 | 0.05 | +43 bearers (+40.6%) | Up 27,018 places |
| 2020 | #150,205 | 109 | 0.04 | -40 bearers (-26.8%) | Down 33,376 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 Iwase 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 | #116,829 | #150,205 | -28.6% |
| Count | 149 | 109 | -26.8% |
| Per 100K | 0.05 | 0.04 | -27.1% |
Between the 2010 and 2020 Census, the number of Iwase bearers went from 149 to 109 (-26.8% change). The surname moved down 33,376 positions in the national ranking, going from #116,829 to #150,205.
FAQ
Iwase surname: questions and answers
How many people in the U.S. have the surname Iwase?
Name Census estimates that about 125 living Americans carry the surname Iwase. Using the current population baseline, that works out to roughly 1 in 2,742,035 residents.
How common is Iwase?
Iwase ranks #150,205 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 109 people with the surname Iwase. That is different from the site's living-bearer estimate (125), 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 Iwase.
Has Iwase become more or less common over time?
Between 2010 and 2020, the surname Iwase went from 149 recorded bearers to 109. That is a decrease of 40 (-26.8%). In the national ranking it fell from #116,829 to #150,205.
What does the Census say about the background of Iwase?
Among Census respondents with the surname Iwase, the largest self-reported group is Asian/Pacific Islander at 98.2%. The next largest groups are White (0.9%) 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?
Asian/Pacific Islander is the largest self-reported group for the surname Iwase in the 2020 Census, accounting for 98.2% (107 people in the source table).
What is the full ancestry breakdown?
Iwase appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are Asian/Pacific Islander (98.2%), White (0.9%), 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 Iwase (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 Iwase mean?
A Japanese surname signifying someone residing near or descended from a rocky shore. 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 Iwase (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 common is the surname Iwase?
Find out how many people have the last name Iwase on our sister site HowManyOfMe.org — a quick modern estimate with the living-bearer count front and centre.