Kasai
Masculine
Kasai is overwhelmingly a boys’ name — 1,065 boys against 18 girls since 1880.
Kasai is the name of one of Africa's great rivers, a wide tributary that gives its name to a whole region of the Congo basin, and it is also an old Japanese place and family name — two unrelated roads to the same three syllables. In American records it is a newcomer, arriving in the late twentieth century and climbing since. It moves in the mouth like Kai with a step added in the middle.
How old is the name Kasai?
Kasai first appears in US birth records in 1996 — 29 years ago. Kasai is overwhelmingly a brand-new baby name right now — most Kasais are still in diapers. About 1,100 people named Kasai are estimated to be alive in the US today.
When was the name Kasai most popular?
Kasai peaked in 2025, reaching #639 nationally. Today it ranks #639, exactly where it peaked. See the whole 2025 chart.
Kasai appears on this list:
Where it comes from
Origin, sound and short forms
The story of Kasai
Kasai reached English speakers as a name on a map before it was a name for a child. The Kasai is a major river of Central Africa, long enough and important enough that the surrounding region and its provinces carry the name; European atlases print it as Kasaï, in the French spelling used across the Congo. Separately and much older, Kasai is a Japanese surname and place name, borne by families whose written forms differ even where the sound is identical. Its use as an American given name for boys is genuinely recent — it appears on the national record only in the last stretch of the twentieth century, and has been rising rather than fading ever since.
Meaningnot established
Not established
No settled meaning attaches to Kasai as a given name. What is documented is where the word already lives: the Kasai River and the Kasai provinces of the Democratic Republic of Congo, and, in Japan, the surname and place name Kasai — a district of eastern Tokyo and a city in Hyōgo Prefecture, written with several different sets of kanji depending on the family.
Pronouncing Kasai
kah-SIGH
Most American speakers land on two beats, kah-SIGH, with stress at the end. The Japanese name is three even beats, KAH-sah-ee, and the Congo river is often said kah-sah-EE. All are defensible, so whichever you choose you will be correcting people occasionally.
Nicknames for Kasai
Moderate
What the data says
146 years of official birth records
The long climb, and where it stands now
The same years in position rather than babies
- First recorded
- 1996
- Most boys named
- 2025437 — the highest on record
- Peak rank
- #639reached in 2025
- Change vs 2024
- +360.0%437 in 2025, from 95
Rank is a position, a count is a headcount, and they move independently — a name can hold its rank while the number of babies behind it falls. Source: U.S. Social Security Administration.
Kasai in other languages
The same name elsewhere
- Kasaï in French — spelling variant
- 葛西 in Japanese — transliteration
Strongest US states over the last decade: Pennsylvania, New York, Florida.
Kasais among us
people named Kasai are estimated to be alive in the US today
About 1 boy in 3,909 born in 2025 was named Kasai
Estimated from SSA birth records and published actuarial life tables. Method
Spellings of Kasai
- #639
- Kasai on the 2025 chart
- #504
- counting every spelling
The SSA counts spellings, not names. Kasai went to 437 boys in 2025, but Casai, Khasai and Kasaii and the rest below are the same name said out loud. Together the 6 spellings went to 510, which makes it the 504th most-given boys’ name of the year — 135 places above the chart.
- Kasai437
- Casai21
- Khasai16
- Kasaii14
- Kazai13
- Khazai9
About 1 boy in 3,349 born in 2025 was given one of these spellings — against 1 in 3,909 for Kasai itself.
Spellings are grouped by a fixed rule that folds interchangeable English spellings of one sound (ck/k, ph/f, x/ks, a non-initial y for i) and keeps vowels apart, so Sean and Shawn stay separate names. It errs towards splitting: a family here is never larger than the truth. SSA national data, 2025. Method
Is it right for you
What happens to a name after it peaks
The Stevan test
Every popular name lives one long story — a climb, a peak, a slow settling back. Kasai's later chapters haven't been written yet, so we borrowed them: Stevan climbed just as high around 1953, and its whole arc is on record. Line the two peaks up, and Stevan's path sketches the road Kasai is walking now.
Kasai is climbing fast right now. Steep climbs tend to come with steep descents — the quicker a name arrives, the more firmly it belongs to its moment.
A scored estimate from 146 years of naming cycles — not a prophecy. Great names outlive statistics. How this is scored
Where Kasai is headed
Kasai looks set to keep climbing gently, with roughly 28% more babies a year by 2030 if the current curve holds. Its history is short or jumpy, though, so read this as a sketch rather than a promise.
Low confidence — fitted on official counts through 2025.
A damped-trend projection of the official birth data — a sketch of momentum, not a promise. Every name's forecast, ranked.
Kasai beside its neighbors
The names ranked closest to Kasai in 2025, in babies rather than position — the bars are to scale.
US boys given each name in 2025.
The trade-off
- Only five letters and three plain vowels — people who hear it can usually spell it, and people who read it are close on the first try.
- Already exists as a real word on the map and in Japanese family registers, so it is a found name rather than a coined one.
- Sits alongside the well-worn Kai, Rai and Zai sounds, so it is unfamiliar as a whole without being unfamiliar in its parts.
- Has been on the US record for long enough to be an established choice rather than a single-year blip, and is still moving upward.
- Stress and syllable count are genuinely unsettled: kah-SIGH, KAH-sah-ee and kah-sah-EE are all heard. Decide which one is yours early, because you will be the one teaching it.
- Said aloud in Japanese, kasai is also the ordinary word for a fire or blaze (火災) — written with different characters from the surname, but the same sound. Worth knowing if the family has Japanese ties.
- He will almost certainly be the only Kasai anywhere in his school, which means no ready-made familiarity: expect Kasey, Kai and Cassie as the usual near-misses on forms and roll calls.
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What they receive
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Kasai
Masculine · #639 in the U.S.
Frequently asked
- How many Kasais are there in the world?
- No country counts the world's names, so there is no worldwide figure — anyone quoting one is estimating. About 1,100 people named Kasai are estimated to be alive in the US today.
- How do you spell Kasai?
- Kasai is the most-used spelling in US records — 437 of the 510 babies given the name in 2025. The others recorded are Casai, Khasai, Kasaii, Kazai and Khazai.
- How popular is the name Kasai in 2025?
- Kasai ranks #639 among US boy names in 2025, with 437 babies given the name.
- How rare is the name Kasai?
- About 1 in every 3,909 US boys born in 2025 was named Kasai — 437 in all.
- Will my child share the name Kasai with classmates?
- Kasai will almost certainly be the only one in school.
Ranked beside Kasai
Names sitting at a similar level of popularity right now.
Memphis#639 · Ronald#637 · Leonard#637 · Julio#641 · Amias#642 · Samir#643 · Izaiah#635 · Shane#635
Looking for what else is popular rather than what resembles Kasai? See the current top 100.
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US figures from the Social Security Administration. 1880–2025. Data & methodology
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