Namewise

Kai vs Sebastian

Kai and Sebastiancompared on official birth-registration statistics and Namewise's recorded data. This page states what each name's record shows — it never picks a winner or scores one name against the other.

Head to head

Ranks are only compared within one published list and one year. Two ranks from different years, from a boys' and a girls' list, or from different registrars are not comparable, so they are not placed side by side.

  • New South Wales, Australia · Boys

    In 2025, Kai was ranked #23 and Sebastian #31 among boys in New South Wales, Australia.

  • Republic of Ireland · Boys

    In 2025, Kai was ranked #34 and Sebastian #125 among boys in Republic of Ireland.

  • England and Wales · Boys

    In 2025, Kai was ranked #78 and Sebastian #47 among boys in England and Wales.

  • Norway · Boys

    In 2025, Kai was ranked #282 and Sebastian #53 among boys in Norway.

  • Scotland · Boys

    In 2024, Kai was ranked #56 and Sebastian #116 among boys in Scotland.

  • Northern Ireland · Boys

    In 2024, Kai was ranked #69 and Sebastian #154 among boys in Northern Ireland.

Kai and Sebastian over time

Kai and Sebastian appear together in 5 published lists, across 163 years of shared records. Sebastian held the stronger position in more years in 3 of them, Kai in 2.

The order between them changed and held in 3 of those lists — a change in that published list, never a claim that one name displaced the other.

Sebastian reached its own highest recorded position earlier in 3 of those lists, Kai in 2. Each position is a place inside its own list, so this compares when they peaked and never how high.

Counted list by list. Two names in the same published list are measured on the same scale in the same year, so those comparisons are real — but positions from different lists are not, so nothing here is combined into an overall standing.

How this pair is related

The relationship kinds these two qualify for, each under its own stated rule. Every one is drawn from a list they both appear in.

  • One moved ahead of the other

    In 2023, Kai moved ahead of Sebastian in New South Wales, Australia · Boys — #26 and #20 the year before became #20 and #27.

  • Repeatedly exchanged positions

    Kai and Sebastian changed places 4 times in England and Wales · Boys between 1996 and 2025, ending at #78 and #47.

  • Closest over the longest run

    Across 30 shared years in England and Wales · Boys, Kai and Sebastian averaged 33.3 places apart, ending at #78 and #47.

  • Longest-running competitions

    Kai and Sebastian were both ranked in England and Wales · Boys for 30 years, from 1996 to 2025, ending at #78 and #47.

  • Peaked in the same years

    Both reached their highest recorded position in New South Wales, Australia · Boys within 2 years — Kai #20 in 2023, Sebastian #20 in 2022.

List by list

  • Norway · Boys58 shared years, 1968–2025

    Kai held the stronger position in 16 of those years, Sebastian in 42.

    Highest recorded here: Kai #57 in 1976, Sebastian #6 in 2006.

    The order changed in 1985: Sebastian moved ahead. In 1984 they stood at #106 and #123; by 1985 that had become #127 and #112.

    Most recent shared year, 2025: Kai #282, Sebastian #53.

  • England and Wales · Boys30 shared years, 1996–2025

    Kai held the stronger position in 13 of those years, Sebastian in 17.

    Highest recorded here: Kai #56 in 2003, Sebastian #28 in 2018.

    The order between them never changed and held in this list.

    Most recent shared year, 2025: Kai #78, Sebastian #47.

  • Republic of Ireland · Boys28 shared years, 1997–2025

    Kai held the stronger position in 19 of those years, Sebastian in 7.

    Highest recorded here: Kai #30 in 2024, Sebastian #80 in 2017.

    The order changed in 2013: Kai moved ahead. In 2012 they stood at #109 and #109; by 2013 that had become #85 and #98.

    Most recent shared year, 2025: Kai #34, Sebastian #125.

  • Northern Ireland · Boys24 shared years, 1999–2024

    Kai held the stronger position in 23 of those years, Sebastian in 1.

    Highest recorded here: Kai #52 in 2021, Sebastian #102 in 2015.

    The order between them never changed and held in this list.

    Most recent shared year, 2024: Kai #69, Sebastian #154.

  • New South Wales, Australia · Boys23 shared years, 2002–2025

    Kai held the stronger position in 4 of those years, Sebastian in 19.

    Highest recorded here: Kai #20 in 2023, Sebastian #20 in 2022.

    The order changed in 2023: Kai moved ahead. In 2022 they stood at #26 and #20; by 2023 that had become #20 and #27.

    Most recent shared year, 2025: Kai #23, Sebastian #31.

Two names moving past each other in a ranking is a fact about the ranking. Namewise does not claim one name displaced the other, that families chose between them, or that either influenced the other — none of that is in this data.

Where to go next

Comparisons that share a name, a rule or a published list with this one. Each is an existing comparison page with its own evidence — nothing here says these pairs are alike.

Other comparisons involving Kai

Pairs where Kai shares a published list with another name, each measured inside one registrar's own list.

Other comparisons involving Sebastian

Pairs where Sebastian shares a published list with another name, each measured inside one registrar's own list.

Other pairs with the same kind of relationship

Pairs that qualify under the same rule as this one — close in one country, far apart in another.

All close in one country, far apart in another→

Other pairs ranked together in the 2020s

Pairs both ranked in the same published list at some point between 2020 and 2029.

The 2020s across all registrars→

Side by side

Side-by-side comparison of Kai, Sebastian
FieldKaiSebastian
Record typeOfficial statistical record (evidence-only)Editorially researched profile
Gender usagemalemale
MeaningNot yet recordedTraditionally interpreted as 'venerable' or 'revered' — from Latin Sebastianus, 'from Sebaste' (a city in Asia Minor), whose own name derives from a Greek word used to translate the Roman imperial title Augustus.
OriginNot yet recordedLatin, from Greek
PronunciationNot yet recorded/səˈbæstʃən/
Syllables13
Common variants / nicknamesNot yet recordedNot yet recorded
Recorded regional usageAU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NOAU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NO, NZ
Most recent popularity observationNew South Wales, Australia · Boys #23 (2025)New South Wales, Australia · Boys #31 (2025)
Pronunciation clarity (demonstration score)Not yet recorded65/100
Spelling simplicity (demonstration score)95/10070/100
International familiarity (demonstration score)100/100100/100
Data Confidencemediummedium

What the data shows

  • Sebastian has a recorded origin (Latin, from Greek); Kai does not have one recorded yet.
  • Kai has 1 syllable, compared with 3 for Sebastian.
  • A meaning is recorded for Sebastian; Kai doesn't have one written yet.
  • Both names have recorded usage in AU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NO.

How each name got here

Kai

Popularity journey

  1. First recorded1945

    First recorded at #76 among boys in Norway in 1945 — the earliest year that source publishes this name, not necessarily the earliest it was used.

    Norway · Boys

  2. Highest recorded2002–2025

    Highest recorded position: #20 among boys in New South Wales, Australia, in 2023 (recorded 2002–2025).

    New South Wales, Australia · Boys

  3. Most recent2025

    Most recently recorded at #4867 among girls in England and Wales, in 2025.

    England and Wales · Girls

Sebastian

Popularity journey

  1. First recorded1968

    First recorded at #415 among boys in Norway in 1968 — the earliest year that source publishes this name, not necessarily the earliest it was used.

    Norway · Boys

  2. Highest recorded1968–2025

    Highest recorded position: #6 among boys in Norway, in 2006 (recorded 1968–2025).

    Norway · Boys

  3. Most recent2025

    Most recently recorded at #47 among boys in England and Wales, in 2025.

    England and Wales · Boys