Isaac vs Kai
Isaac and Kaicompared 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, Isaac was ranked #26 and Kai #23 among boys in New South Wales, Australia.
Northern Ireland · Boys
In 2024, Isaac was ranked #26 and Kai #69 among boys in Northern Ireland.
Republic of Ireland · Boys
In 2025, Isaac was ranked #104 and Kai #34 among boys in Republic of Ireland.
England and Wales · Boys
In 2024, Isaac was ranked #37 and Kai #72 among boys in England and Wales.
Scotland · Boys
In 2024, Isaac was ranked #49 and Kai #56 among boys in Scotland.
Norway · Boys
In 2025, Isaac was ranked #251 and Kai #282 among boys in Norway.
Isaac and Kai over time
Isaac and Kai appear together in 5 published lists, across 148 years of shared records. Isaac held the stronger position in more years in 4 of them, Kai in 1.
The order between them changed and held in 2 of those lists — a change in that published list, never a claim that one name displaced the other.
Isaac 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 2016, Kai moved ahead of Isaac in Republic of Ireland · Boys — #77 and #80 the year before became #98 and #92.
- Repeatedly exchanged positions
Isaac and Kai changed places 7 times in Norway · Boys between 1974 and 2025, ending at #251 and #282.
- Closest over the longest run
Across 29 shared years in England and Wales · Boys, Isaac and Kai averaged 35.5 places apart, ending at #37 and #72.
- Longest-running competitions
Isaac and Kai were both ranked in Norway · Boys for 41 years, from 1974 to 2025, ending at #251 and #282.
- Peaked in the same years
Both reached their highest recorded position in Northern Ireland · Boys within 2 years — Isaac #20 in 2020, Kai #52 in 2021.
List by list
Norway · Boys41 shared years, 1974–2025
Isaac held the stronger position in 18 of those years, Kai in 23.
Highest recorded here: Isaac #164 in 2014, Kai #73 in 1974.
The order changed in 2025: Isaac moved ahead. In 2024 they stood at #262 and #211; by 2025 that had become #251 and #282.
Most recent shared year, 2025: Isaac #251, Kai #282.
England and Wales · Boys29 shared years, 1996–2024
Isaac held the stronger position in 26 of those years, Kai in 3.
Highest recorded here: Isaac #20 in 2015, Kai #56 in 2003.
The order between them never changed and held in this list.
Most recent shared year, 2024: Isaac #37, Kai #72.
Republic of Ireland · Boys28 shared years, 1997–2025
Isaac held the stronger position in 16 of those years, Kai in 12.
Highest recorded here: Isaac #77 in 2014, Kai #30 in 2024.
The order changed in 2016: Kai moved ahead. In 2015 they stood at #77 and #80; by 2016 that had become #98 and #92.
Most recent shared year, 2025: Isaac #104, Kai #34.
Northern Ireland · Boys27 shared years, 1998–2024
Isaac held the stronger position in 25 of those years, Kai in 2.
Highest recorded here: Isaac #20 in 2020, Kai #52 in 2021.
The order between them never changed and held in this list.
Most recent shared year, 2024: Isaac #26, Kai #69.
New South Wales, Australia · Boys23 shared years, 2002–2025
Isaac held the stronger position in 21 of those years, Kai in 2.
Highest recorded here: Isaac #8 in 2015, Kai #20 in 2023.
The order between them never changed and held in this list.
Most recent shared year, 2025: Isaac #26, Kai #23.
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.
Side by side
| Field | Isaac | Kai |
|---|---|---|
| Record type | Editorially researched profile | Official statistical record (evidence-only) |
| Gender usage | male | male |
| Meaning | Traditionally understood as 'he will laugh' or 'he laughs', tied to the biblical narrative in which Abraham and Sarah laugh at the prophecy of Isaac's birth in their old age. | Not yet recorded |
| Origin | Biblical Hebrew, transmitted into English via Greek Isaak and Late Latin Isaac | Not yet recorded |
| Pronunciation | /ˈaɪzək/ | Not yet recorded |
| Syllables | 2 | 1 |
| Common variants / nicknames | Not yet recorded | Not yet recorded |
| Recorded regional usage | AU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NO, NZ | AU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NO |
| Most recent popularity observation | New South Wales, Australia · Boys #26 (2025) | New South Wales, Australia · Boys #23 (2025) |
| Pronunciation clarity (demonstration score) | 90/100 | Not yet recorded |
| Spelling simplicity (demonstration score) | 94/100 | 95/100 |
| International familiarity (demonstration score) | 100/100 | 100/100 |
| Data Confidence | medium | medium |
What the data shows
- Isaac has a recorded origin (Biblical Hebrew, transmitted into English via Greek Isaak and Late Latin Isaac); Kai does not have one recorded yet.
- Isaac has 2 syllables, compared with 1 for Kai.
- A meaning is recorded for Isaac; 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
Isaac
Popularity journey
First recorded1964
First recorded at #232 among boys in Republic of Ireland in 1964 — the earliest year that source publishes this name, not necessarily the earliest it was used.
Republic of Ireland · Boys
Highest recorded1990–2025
Highest recorded position: #8 among boys in New South Wales, Australia, in 2015 (recorded 1990–2025).
New South Wales, Australia · Boys
Most recent2025
Most recently recorded at #26 among boys in New South Wales, Australia, in 2025.
New South Wales, Australia · Boys
Kai
Popularity journey
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
Highest recorded2002–2025
Highest recorded position: #20 among boys in New South Wales, Australia, in 2023 (recorded 2002–2025).
New South Wales, Australia · Boys
Most recent2025
Most recently recorded at #23 among boys in New South Wales, Australia, in 2025.
New South Wales, Australia · Boys