Kai
Masculine · Latin roots · “Sea (Hawaiian”
Kai is given to both — 70,232 boys and 8,478 girls since 1880. See Kai as a girl nameSee other names given to both
Kai is one of those rare short names that several unrelated languages arrived at independently: it is the word for sea in Hawaiian, it can be written with the character for sea in Japanese, and along the North Sea coast Frisian, Danish and German families have used Kai and Kaj for centuries. Three letters, one syllable, and very nearly the same sound in the mouth wherever it lands. It charts in Scotland, Canada and England & Wales as well as here — a name that needs no translating at a border.
How old is the name Kai?
Kai first appears in US birth records in 1926 — 99 years ago. The typical Kai is a kid of about 8 — this name's wave is very recent. About 69,500 people named Kai are estimated to be alive in the US today.
When was the name Kai most popular?
Kai peaked in 2022, reaching #59 nationally. Today it ranks #93, 34 places below that high. See the whole 2022 chart.
Where it comes from
From Gaius (Latin) to Kai
The story of Kai
There is no single origin here, and that is the honest pleasure of the name. In the Pacific it is a plain noun — kai, the sea — and in Japan it has long been a men's name written with several possible characters. Along the North Sea coast, Frisian, Danish and German records carry Kai and Kaj as men's names going back centuries, generally traced either to a shortened Germanic name or to the Latin Gaius, the same root scholars propose for Welsh Cai, the knight who reaches English romance as Sir Kay. American use is a much newer story: the name appeared on the records early in the twentieth century, stayed quiet for decades, then rose in earnest within living memory, and it is strongest today in California, Texas and Florida.
Meaningscholars disagree
Sea (Hawaiian, and one common Japanese writing); triumph in Chinese; in northern Europe a short form linked to Latin Gaius
These are separate names that met at one spelling rather than rival guesses about a single word. Hawaiian kai is the sea. Japanese Kai is written with different characters depending on the family, among them 海 (sea) and 快 (pleasant). Chinese kǎi, 凯, carries the sense of triumph. The Frisian and Scandinavian Kai/Kaj is usually explained either as a clipping of a longer Germanic name or as a descendant of the Latin Gaius. All four are well documented; which one applies depends on whose family is doing the naming.
How the name formed
- GaiusLatin
- CaiWelsh
- KayArthurian English
- Kai / KajFrisian, Danish
- Kai
Related forms: Kaj · Cai · Kay · 海 / カイ · 凯 · Caio
Pronouncing Kai
KY
Rhymes with sky. In Hawaiian and Japanese the vowel is closer to two quick sounds, kah-ee, sliding together; American English settles firmly on the single KY. Misreadings are rare once heard.
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
- 1926
- Most boys named
- 20225,374 — the highest on record
- Peak rank
- #59reached in 2022
- Change vs 2023
- −24.3%3,768 in 2025, from 4,976
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.
Kai in other languages
The same name elsewhere
- Kaj in Danish, Swedish — spelling variant
- Cai in Welsh — related form
- Kay in English — related form
- 海 / カイ in Japanese — transliteration
- 凯 in Chinese — transliteration
- Caio in Italian, Portuguese — related form
Strongest US states over the last decade: California, Texas, Florida. International figures from National Records of Scotland, Statistics Canada, Office for National Statistics. Sources
Kais among us
people named Kai are estimated to be alive in the US today
About 1 boy in 453 born in 2025 was named Kai
Estimated from SSA birth records and published actuarial life tables. Method
Is it right for you
What happens to a name after it peaks
The Carlos test
Every popular name lives one long story — a climb, a peak, a slow settling back. Kai's later chapters haven't been written yet, so we borrowed them: Carlos climbed just as high around 1999, and its whole arc is on record. Line the two peaks up, and Carlos's path sketches the road Kai is walking now.
Kai sits in the calm middle of the cycle — neither chasing a wave nor sliding off one. Middle-of-the-cycle names age slowly and predictably.
A scored estimate from 146 years of naming cycles — not a prophecy. Great names outlive statistics. How this is scored
Where Kai is headed
Kai should hold steady through 2030 — the curve is flat, and flat curves are the most predictable kind.
Medium 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.
Kai beside its neighbors
The names ranked closest to Kai in 2025, in babies rather than position — the bars are to scale.
US boys given each name in 2025.
The trade-off
- One syllable, three letters: nothing to shorten, nothing to abbreviate, and it fits every form and roster without trouble.
- The same sound carries in Hawaiian, Japanese, Chinese, Danish and English settings with no adjustment asked of anyone.
- Recognized well beyond the US — it also charts in Scotland, Canada and England & Wales.
- Doubles as the everyday form of Malakai, Nikolai, Makai and Kaiden, so it sits comfortably beside a longer name on a birth certificate.
- Familiar to American ears while still uncrowded; a child will likely be the only one in the classroom.
- Nearly every child given this spelling is a boy. A girl named Kai will meet that assumption on paperwork and rosters from time to time — worth knowing in advance rather than being surprised by.
- Kye, Cai, Kaj and Ky all sound identical, so the spelling will occasionally need saying aloud, even though K-A-I is the version most Americans write first.
- Because it also works as the short form of longer names, some Kais get asked whether it is short for something. A one-word answer usually settles it.
- The American wave is recent, so most people carrying the name are still children. That changes on its own as they grow, the way it does for every newly risen name.
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What they receive
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Kai
Masculine · Latin roots · #93 in the U.S.
Frequently asked
- How many Kais are there in the world?
- No country counts the world's names, so there is no worldwide figure — anyone quoting one is estimating. About 69,500 people named Kai are estimated to be alive in the US today.
- How popular is the name Kai in 2025?
- Kai ranks #93 among US boy names in 2025, with 3,768 babies given the name.
- How common is the name Kai?
- About 1 in every 453 US boys born in 2025 was named Kai — 3,768 in all.
- Will my child share the name Kai with classmates?
- Kai will almost certainly be the only one in school.
Ranked beside Kai
Names sitting at a similar level of popularity right now.
Emiliano#94 · Robert#92 · Jose#95 · Leonardo#91 · Christian#96 · Micah#90 · Jonathan#89 · Eithan#97
Looking for what else is popular rather than what resembles Kai? See the current top 100.
Choosing between Kai and another name?
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US figures from the Social Security Administration; international figures from national statistics agencies. 1880–2025. Data & methodology
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