Kai
Feminine · Latin roots · “Sea (Hawaiian”
Kai is given to both — 8,478 girls and 70,232 boys since 1880. See Kai as a boy 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 1953 — 72 years ago. The typical Kai alive today was born around 2011, making them about 14 years old. About 8,400 people named Kai are estimated to be alive in the US today.
When was the name Kai most popular?
Kai peaked in 2021, reaching #768 nationally. Today it ranks #1053, 285 places below that high. See the whole 2021 chart.
Kai appears on this list:
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
- 1953
- Most girls named
- 2021371 — the highest on record
- Peak rank
- #768reached in 2021
- Change vs 2024
- +9.3%234 in 2025, from 214
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: Texas, California, Florida.
Kais among us
people named Kai are estimated to be alive in the US today
About 1 girl in 6,869 born in 2025 was named Kai
Estimated from SSA birth records and published actuarial life tables. Method
Spellings of Kai
- #1053
- Kai on the 2025 chart
- #660
- counting every spelling
The SSA counts spellings, not names. Kai went to 234 girls in 2025, but Kay, Khai and Cai are the same name said out loud. Together the 4 spellings went to 315, which makes it the 660th most-given girls’ name of the year — 393 places above the chart.
- Kai234
- Kay37
- Khai32
- Cai12
About 1 girl in 5,102 born in 2025 was given one of these spellings — against 1 in 6,869 for Kai 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 Jaquelin 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: Jaquelin climbed just as high around 2000, and its whole arc is on record. Line the two peaks up, and Jaquelin'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 is easing off slowly — about 20% fewer babies a year by 2030 if the trend continues.
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 girls 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
Feminine · Latin roots · #1053 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 8,400 people named Kai are estimated to be alive in the US today.
- How do you spell Kai?
- Kai is the most-used spelling in US records — 234 of the 315 babies given the name in 2025. The others recorded are Kay, Khai and Cai.
- How popular is the name Kai in 2025?
- Kai ranks #1053 among US girl names in 2025, with 234 babies given the name.
- How rare is the name Kai?
- About 1 in every 6,869 US girls born in 2025 was named Kai — 234 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.
Jubilee#1053 · Maelynn#1053 · Melani#1053 · Araya#1052 · Jazlynn#1057 · Sapphire#1057 · Harlee#1047 · Inara#1047
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. 1880–2025. Data & methodology
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