Kasai
Kasai was the 639th most popular name for boys in 2025, given to 437 babies. That is its highest rank since records began in 1880. Over the last ten years it has moved up 5,237 places. More babies were named Kasai in the 2020s than in any other decade.
Meaning Origin not documented
Say it kuh-SY /kəˈsaɪ/
- Rank in 2025
- #639 boys, up 1,847 places since 2020
- Babies in 2025
- 437boys
- Girls and boys
- Almost always a boy’s name2021–2025
- Peak year
- 2025437 babies
- Total since 1880
- 1,083babies recorded
What does the name Kasai mean?
Kasai is a recent American boys' name whose source is not documented. The same word has several unrelated uses: it is a Japanese surname (written 葛西, 河西 or 笠井), a Japanese city, and the name of a large river in Central Africa, a tributary of the Congo. None of the sources consulted says which, if any, led to its use as a first name in the US, so no meaning is given.
How sure is this? Not documented. Several unrelated sources share the spelling; none is documented as the source of the US given name.
Sources for this meaning
- Wiktionary, entry 'Kasai', Wiktionary (Wikimedia Foundation)
- Wikipedia, 'Kasai (surname)', Wikipedia (Wikimedia Foundation)
- Wikipedia, 'Kasai River', Wikipedia (Wikimedia Foundation)
- US Social Security Administration, national baby-name data 1880-2025 (usage history only), US Social Security Administration
Kasai popularity since 1880
A few girls are given the name too: 18 since 2019, 7 in 2025.
| Year | Rank (boys) | Babies (boys) |
|---|---|---|
| 2025 | #639 | 437 |
| 2020 | #2,486 | 52 |
| 2010 | #10,225 | 7 |
| 2000 | #7,829 | 8 |
| 1990 | — | — |
| 1980 | — | — |
| 1970 | — | — |
| 1960 | — | — |
| 1950 | — | — |
| 1940 | — | — |
| 1930 | — | — |
| 1920 | — | — |
| 1910 | — | — |
| 1900 | — | — |
| 1890 | — | — |
| 1880 | — | — |
How popular is Kasai, counting every spelling?
Kasai is the most common spelling of a name family that ranked #598 for boys in 2025 once every spelling is counted together, compared with #639 for Kasai on its own. Together these spellings went to 471 boys in 2025.
| Spelling | Babies 2025 | Official rank | Babies 2021–2025 |
|---|---|---|---|
| Kasai | 437 | #639 | 698 |
| Casai | 21 | #4,732 | 29 |
Spellings count together when they sound the same in American English and are used for the same sex; nicknames and forms that sound different (such as Theo and Theodore) are kept apart. How we group spellings.
How many kids will share the name Kasai?
437 of the 3,606,400 babies born in the US in 2025 were named Kasai (0.12 per 1,000 births). For a boy named Kasai born in 2025, the chance that another child with the same name is in a class of 20 children the same age is under 1 in 50. If every grade liked the name as much as the 2025 babies do, only about one elementary school in 19 (of 430 pupils) would have a child named Kasai.
Shares of all registered births (NCHS); classes assumed to be children born the same year. How we estimate this.
How old are people named Kasai?
About 1,100 people born in the US named Kasai are alive today, with a median age of 2; half are between 1 and 7. That makes Kasai a young name: most people with it are children.
Babies given the name each year (SSA) times the share of that birth year still alive (SSA life tables). Counts people born in the US only. Method.
Kasai by state
How common Kasai was among boys born in each state in 2021–2025. It is notably more common than nationally in Pennsylvania (3.0×), New Jersey (1.9×), New York (1.7×), Georgia (1.6×), North Carolina (1.6×). In 25 states fewer than five boys a year got the name, too few for SSA to publish, so those states show as zero.
Names with a similar history
These names rose and fell in step with Kasai: their share of US boys followed the most similar curve since 1880. If you like Kasai, they share its era and feel.
Middle names for Kasai · Sibling names for Kasai
Questions about the name Kasai
How popular is the name Kasai?
Kasai was the 639th most popular name for boys in 2025, given to 437 babies. That is its highest rank since records began in 1880. Over the last ten years it has moved up 5,237 places. More babies were named Kasai in the 2020s than in any other decade.
Is Kasai a boy or girl name?
In 2021–2025, almost always a boy’s name given the name Kasai in the US.
Where is Kasai most popular?
In 2021–2025, Kasai was most common in Delaware (0.92 per 1,000 boys), followed by Pennsylvania and New Jersey.