Jack vs Leo
Jack and Leocompared 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.
Republic of Ireland · Boys
In 2025, Jack was ranked #2 and Leo #10 among boys in Republic of Ireland.
New Zealand · Boys
In 2023, Jack was ranked #4 and Leo #5 among boys in New Zealand.
Northern Ireland · Boys
In 2024, Jack was ranked #4 and Leo #12 among boys in Northern Ireland.
England and Wales · Boys
In 2024, Jack was ranked #22 and Leo #5 among boys in England and Wales.
New South Wales, Australia · Boys
In 2025, Jack was ranked #10 and Leo #5 among boys in New South Wales, Australia.
Scotland · Boys
In 2024, Jack was ranked #7 and Leo #5 among boys in Scotland.
Norway · Boys
In 2025, Jack was ranked #432 and Leo #28 among boys in Norway.
Jack and Leo over time
Jack and Leo appear together in 6 published lists, across 202 years of shared records. Jack held the stronger position in more years in 5 of them, Leo in 1.
The order between them changed and held in 4 of those lists — a change in that published list, never a claim that one name displaced the other.
Jack reached its own highest recorded position earlier in 6 of those lists, and Leo in none. 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 2019, Leo moved ahead of Jack in England and Wales · Boys — #5 and #6 the year before became #8 and #6.
- Repeatedly exchanged positions
Jack and Leo changed places 4 times in New Zealand · Boys between 2003 and 2023, ending at #4 and #5.
- Closest over the longest run
Across 29 shared years in England and Wales · Boys, Jack and Leo averaged 54.6 places apart, ending at #22 and #5.
- Mirrored each other
Over 21 shared years in New Zealand · Boys, Leo rose about as far as Jack fell — from #2 and #86 in 2003 to #4 and #5 in 2023.
- Longest-running competitions
Jack and Leo were both ranked in Norway · Boys for 54 years, from 1947 to 2025, ending at #432 and #28.
List by list
Norway · Boys54 shared years, 1947–2025
Jack held the stronger position in 23 of those years, Leo in 31.
Highest recorded here: Jack #151 in 1956, Leo #28 in 2025.
The order changed in 1997: Leo moved ahead. In 1996 they stood at #329 and #369; by 1997 that had become #359 and #330.
Most recent shared year, 2025: Jack #432, Leo #28.
Republic of Ireland · Boys53 shared years, 1970–2025
Jack held the stronger position in 40 of those years, Leo in 13.
Highest recorded here: Jack #1 in 2000, Leo #10 in 2025.
The order changed in 1986: Jack moved ahead. In 1985 they stood at #170 and #138; by 1986 that had become #128 and #172.
Most recent shared year, 2025: Jack #2, Leo #10.
England and Wales · Boys29 shared years, 1996–2024
Jack held the stronger position in 23 of those years, Leo in 6.
Highest recorded here: Jack #1 in 1996, Leo #5 in 2022.
The order changed in 2019: Leo moved ahead. In 2018 they stood at #5 and #6; by 2019 that had become #8 and #6.
Most recent shared year, 2024: Jack #22, Leo #5.
Northern Ireland · Boys28 shared years, 1997–2024
Jack held the stronger position in 28 of those years, Leo in 0.
Highest recorded here: Jack #1 in 2001, Leo #6 in 2023.
The order between them never changed and held in this list.
Most recent shared year, 2024: Jack #4, Leo #12.
New Zealand · Boys21 shared years, 2003–2023
Jack held the stronger position in 19 of those years, Leo in 2.
Highest recorded here: Jack #1 in 2005, Leo #3 in 2019.
The order between them never changed and held in this list.
Most recent shared year, 2023: Jack #4, Leo #5.
New South Wales, Australia · Boys17 shared years, 2009–2025
Jack held the stronger position in 12 of those years, Leo in 5.
Highest recorded here: Jack #2 in 2009, Leo #3 in 2022.
The order changed in 2022: Leo moved ahead. In 2021 they stood at #3 and #6; by 2022 that had become #6 and #3.
Most recent shared year, 2025: Jack #10, Leo #5.
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 | Jack | Leo |
|---|---|---|
| Record type | Editorially researched profile | Editorially researched profile |
| Gender usage | male | male |
| Meaning | God is gracious (via John), though now used as an independent name. | Lion. |
| Origin | English, historically a diminutive of John | Latin |
| Pronunciation | /ˈdʒæk/ | /ˈliːoʊ/ |
| Syllables | 1 | 1 |
| Common variants / nicknames | Jankin | 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, NZ |
| Most recent popularity observation | Republic of Ireland · Boys #2 (2025) | New South Wales, Australia · Boys #5 (2025) |
| Pronunciation clarity (demonstration score) | 90/100 | 90/100 |
| Spelling simplicity (demonstration score) | 95/100 | 95/100 |
| International familiarity (demonstration score) | 100/100 | 100/100 |
| Data Confidence | high | medium |
What the data shows
- Jack is recorded with a English, historically a diminutive of John origin, while Leo is recorded with a Latin origin.
- Jack and Leo both have 1 syllable.
- Jack's recorded meaning differs from Leo's — see the table above for each.
- Both names have recorded usage in AU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NO, NZ.
- The available evidence gives Jack a "high" Data Confidence level and Leo a "medium" level — this reflects how complete and corroborated the underlying evidence is, not a judgement of either name.
How each name got here
Jack
Popularity journey
First recorded1945
First recorded at #171 among boys in Norway in 1945 — the earliest year that source publishes this name, not necessarily the earliest it was used.
Norway · Boys
Highest recorded1996–2024
Highest recorded position: #1 among boys in England and Wales, in 1996 (recorded 1996–2024).
England and Wales · Boys
Most recent2025
Most recently recorded at #10 among boys in New South Wales, Australia, in 2025.
New South Wales, Australia · Boys
Leo
Popularity journey
First recorded1947
First recorded at #303 among boys in Norway in 1947 — the earliest year that source publishes this name, not necessarily the earliest it was used.
Norway · Boys
Highest recorded2009–2025
Highest recorded position: #3 among boys in New South Wales, Australia, in 2022 (recorded 2009–2025).
New South Wales, Australia · Boys
Most recent2025
Most recently recorded at #5 among boys in New South Wales, Australia, in 2025.
New South Wales, Australia · Boys