Head to head · Boys' names
Kasai vs Koen
#639 vs #622 in 2025 · both climbing the charts fast
Koen is a whisker ahead (#622 vs #639 in 2025) and both are climbing the charts fast. The records will not split these two — sound, story and your own last name will.
Cast your vote
Which one would you pick?
Your gut first, the numbers after — the split shows once you pick.
The tale of the tape
On the charts, Koen leads 4 measures of 6; Kasai leads 1.
Ranks, counts and years are measured in the official US birth record; the classroom and living figures are estimates computed from it. The dot marks the side each measure favours on the charts — more common, not better.
What the records say
146 years of US births, drawn on one scale
Two curves, one scale
Who owned which decade
- 1990s: Kasai #8445, Koen #5932 — Koen higher
- 2000s: Kasai #7815, Koen #1626 — Koen higher
- 2010s: Kasai #6205, Koen #1094 — Koen higher
- 2020s: Kasai #2046, Koen #818 — Koen higher
Koen stood higher in every recorded decade — 4 of 4.
Rank by decade
| Decade | Kasai | Koen |
|---|---|---|
| 1990s | #8445 | #5932 |
| 2000s | #7815 | #1626 |
| 2010s | #6205 | #1094 |
| 2020s | #2046 | #818 |
Average national rank across each decade. A dash means the name sat outside the recorded top of that decade.
The names themselves
Meaning, roots, sound and the people who carried each
Where each name comes from
Kasai
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.
How it traveled
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.
Koen
bold counsel
Two roads meet at this spelling. As the Dutch short form of Koenraad (German Konrad, English Conrad), it comes from Germanic kuoni, 'bold, brave', and rad, 'counsel, advice' — that reading is well established. In American use, the same four letters also serve as a respelling of the surname Cohen, from Hebrew kohen, 'priest'. Which one a family means depends entirely on the family.
Chuonrat (Old High German) → Konrad → Conrad → Koenraad (Dutch) → Koen
How it traveled
The Germanic compound behind Konrad — bold plus counsel — was a favorite among medieval German nobility and was carried by German kings and Holy Roman emperors in the Middle Ages. Dutch reshaped it into Koenraad, and Koen broke off as the ordinary spoken form, eventually detaching completely and being registered as a name in its own right.
Where a reading is contested the note says so — this page does not turn a guess into a fact. The chain is each name's recorded forms, oldest first; the story is its opening, told in full on the name's own page.
Out loud, and in short
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.
- Kas — The obvious first-syllable shortening; informal, not an inherited tradition, since the name is too new to have built one.
- Sai — Informal clipping of the back half; also stands alone as a given name in its own right.
- Kai — Used informally by families who want a one-syllable call name; a very well-established independent given name in the US.
Koen
KOH-en
Most American families say it in two syllables, KOH-en, as with Cohen. The Dutch pronunciation is one syllable, koon, since Dutch 'oe' is an 'oo' sound. Said in American English that single-syllable version lands very close to a racial slur, which is a large part of why the two-syllable reading dominates here. Worth deciding which you want before the birth announcement goes out.
- Koen — Historically the short form of Koenraad, now used as a full legal name in its own right across the Dutch-speaking world.
- Koenie — Dutch diminutive, affectionate and informal; mostly used with small children.
- Ko — A further Dutch clipping, informal and old-fashioned in the Netherlands.
Is it right for you
The differences that decide it, laid out by what you want
Choose by what you want
Choose Kasai if you want…
- a name fewer children share#639 in 2025 — kasai will almost certainly be the only one in school
- a name on the way upup 1,828 places on the charts in five years
- a name with more sound in itKasai runs 2 syllables, Koen 1
Choose Koen if you want…
- a name most people already know#622 in 2025, 448 babies that year
- a name with fewer syllablesKoen is 1 syllable to Kasai's 2
Each line is a measured difference between the two names — a rank, a count, a recorded form — never a judgement of either. Save the one that answers your question; it lands on your shortlist.
The trade-offs, name by name
Kasai
Strengths
- 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.
To consider
- 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.
Koen
Strengths
- Short, four letters, and phonetically regular once the pronunciation is agreed — no silent letters and nothing to trim.
- A genuinely old name behind a modern-looking spelling: the Conrad line runs back to medieval Germany.
- Established as a standalone given name in Dutch, so it needs no longer formal version on documents.
To consider
- The spelling will be questioned constantly. Cohen, Coen, Kohen and Conan are all close enough to be guessed, and each has its own pronunciation attached, so expect to correct both letters and sound.
- Because Koen doubles as a respelling of Cohen, some people will hear a Jewish priestly title used as a first name. That use is objectionable to a number of Jewish families, and it is better to know that now than to learn it later.
- In the US this name is worn almost entirely by children, so it currently reads as new here even though it is centuries old in Dutch. That also means very few other boys will share it in a classroom.
Documented properties of each name — how it spells, travels and shortens — not opinions about the child.
With your last name
Say both in full. The notes are facts about letters and sound — a rhyme, a shared initial, the monogram — not a verdict on either name.
Type a last name to hear Kasai and Koen in full.
Weighing the whole shortlist? Run the full comparison — up to eight names with your last name, initials, classroom projections and a printable report.
Decide together
Nobody names a baby alone
Still torn between Kasai and Koen?
Put both to the vote.
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More head-to-heads
Same measures, different pair. Sixty more are dealt daily in the arena.
Lists that carry both names
Every list here names both Kasai and Koen — the same style, ranked by the same records.
Kasai or Koen — the short answers
- Which is more popular, Kasai or Koen?
- Koen, in 2025: Koen ranked #622 with 448 babies; Kasai ranked #639 with 437 babies.
- Which name is rising faster, Kasai or Koen?
- Kasai. Over the last five years Kasai moved up 1,828 places; Koen moved up 567 places.
- Which is the older name, Kasai or Koen?
- Kasai entered the US charts in 1996; Koen entered the US charts in 1996. The record dates them to the same year.
- How many people are named Kasai and Koen?
- About 1,100 people named Kasai are estimated to be alive in the US today. About 5,100 people named Koen are estimated to be alive in the US today.
- Will there be other Kasais or Koens in the classroom?
- Kasai will almost certainly be the only one in school. Koen will almost certainly be the only one in school.
US figures from the Social Security Administration, 1880–2025. Votes are battle voters on this site, not the birth record. Data & methodology
Keep playing
Sixty more head-to-heads are dealt in the arena every day — or line up Kasai, Koen and the rest of your shortlist with your last name in one printable report.
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