Head to head · Boys' names
Kaysen vs Killian
#415 vs #417 in 2025
Kaysen is a whisker ahead (#415 vs #417 in 2025), but the curves point different ways: Kaysen is climbing the charts fast, Killian is stepping back from its peak.
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
The tape is even: Kaysen and Killian each lead 3 measures of 6.
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
- 1910s: Kaysen —, Killian #3825 — Killian higher
- 1920s: Kaysen —, Killian #4286 — Killian higher
- 1980s: Kaysen —, Killian #3726 — Killian higher
- 1990s: Kaysen #7505, Killian #1114 — Killian higher
- 2000s: Kaysen #4026, Killian #1008 — Killian higher
- 2010s: Kaysen #873, Killian #508 — Killian higher
- 2020s: Kaysen #544, Killian #370 — Killian higher
Killian stood higher in every recorded decade — 7 of 7.
Rank by decade
| Decade | Kaysen | Killian |
|---|---|---|
| 1910s | — | #3825 |
| 1920s | — | #4286 |
| 1980s | — | #3726 |
| 1990s | #7505 | #1114 |
| 2000s | #4026 | #1008 |
| 2010s | #873 | #508 |
| 2020s | #544 | #370 |
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
Kaysen
Not established
No etymology has been established for Kaysen. What is documented is the company it keeps: it appears in American records alongside Kayden, Kason, Cason and Kayson, and it ends in the -sen/-son element that in older surnames meant "son of". Whether any particular parent had that in mind, or simply liked the sound, is not something the record preserves.
Our story of Kaysen — where the record runs out
Think of the two halves of this name arriving from different directions. The -sen ending has been traveling for centuries in surnames — Hansen, Jansen, Jackson — where it once marked a line of descent.
Killian
linked either to the Irish word for church or to a root meaning strife
One reading traces Cillian to Old Irish cell, 'church' or 'monastic cell', giving a sense of 'of the church' — fitting for a name spread by missionaries. The other traces it to the personal name Ceallach, whose own meaning is disputed between 'strife' and, again, 'church'. Scholars have not settled it, and both readings sit inside the same small cluster of early Irish words.
Ceallach → Cillian → Kilian → Killian
How it traveled
The name begins as Cillian in early medieval Ireland, in the era when Irish monks were crossing into continental Europe. One of them, Kilian, reached Franconia in the seventh century and was killed at Würzburg; his cult made the name a permanent German fixture as Kilian, complete with a summer feast day still marked in the city.
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
Kaysen
KAY-sen
Two syllables, stress on the first. The ending is the same sound as in Hansen or Jansen. Kayson, Kason and Cason are all said the same way.
- Kay — The most natural short form; also stands alone as a given name in English, more often for girls.
- Kays — Informal clipping, used much as Jacks is used for Jackson.
- KJ — Initials-style nickname where the middle name allows it; common practice among American boys.
Killian
KIL-ee-un
Three light syllables with the stress on the first. The Irish Cillian is said the same way, so switching spellings changes nothing you hear.
- Kil — The most obvious clipping, used informally within families rather than as a standalone name.
- Killy — Informal and affectionate, common in childhood and often dropped later.
- Kili — A softer written form of the same clipping; not established as an independent given name in English.
Is it right for you
The differences that decide it, laid out by what you want
Choose by what you want
Choose Kaysen if you want…
- a name on the way upup 147 places on the charts in five years
Choose Killian if you want…
- a name past its most crowded yearsKillian is stepping back from its peak
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
Kaysen
Strengths
- Reads correctly on first sight for English speakers — no pronunciation guessing, no correcting teachers.
- Two short syllables, easy for a small child to say and to write.
- Sits inside a familiar sound family with Mason, Jackson and Kayden, so it is never strange to an American ear.
To consider
- The spelling has close rivals — Kayson, Kason, Cason, Casen — all pronounced identically. Expect to spell it aloud fairly often, and expect the occasional form to come back with a C.
- Its entire record belongs to one recent stretch of time, so the name will read clearly as belonging to this generation. That can be a pleasure or a limitation, depending on how you feel about a name that dates its bearer.
- Because the name is young, it has no long-settled nickname the way Charles has Charlie. Whatever the family lands on is likely to be the family's own invention.
Killian
Strengths
- One pronunciation, stated by the spelling — people rarely need to be corrected twice.
- A documented line back to early medieval Ireland, with an unbroken German life through the saint of Würzburg.
- Works across Irish, German, French and Central European forms, all recognizable to an English speaker.
To consider
- The first four letters spell an English word, and children notice that sort of thing. It passes quickly for most, but it is the one thing worth saying aloud before you decide.
- Killian and Cillian now compete, and the Irish spelling has grown visible enough that you should expect to specify which one you mean — at the pediatrician, on forms, in email.
- Its American wave is recent, so most people carrying it are still young. That means fewer adult namesakes to point to, and a name that reads as contemporary rather than inherited.
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 Kaysen and Killian 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 Kaysen and Killian?
Put both to the vote.
One link to your partner, your parents, your sister. Each of them gets the two names, a one-tap answer and room to say why — and every reply lands in one place.
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More than two in the running? Settle it with a bracket or run the full comparison with your last name.
More head-to-heads
Same measures, different pair. Sixty more are dealt daily in the arena.
Lists these names appear on
Where Kaysen and Killian each sit in the library — alternatives in the same style, ranked by the same records.
Kaysen or Killian — the short answers
- Which is more popular, Kaysen or Killian?
- Kaysen, in 2025: Kaysen ranked #415 with 772 babies; Killian ranked #417 with 770 babies.
- Which name is rising faster, Kaysen or Killian?
- Kaysen. Over the last five years Kaysen moved up 147 places; Killian moved down 65 places.
- Which is the older name, Kaysen or Killian?
- Kaysen entered the US charts in 1998; Killian entered the US charts in 1915. On the American record, Killian is the older name.
- How many people are named Kaysen and Killian?
- About 6,600 people named Kaysen are estimated to be alive in the US today. About 16,000 people named Killian are estimated to be alive in the US today.
- Will there be other Kaysens or Killians in the classroom?
- Kaysen will almost certainly be the only one in school. Killian 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 Kaysen, Killian and the rest of your shortlist with your last name in one printable report.
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