Namewise

Leo vs Theo

Leo and Theocompared 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.

  • Scotland · Boys

    In 2024, Leo was ranked #5 and Theo #4 among boys in Scotland.

  • England and Wales · Boys

    In 2024, Leo was ranked #5 and Theo #12 among boys in England and Wales.

  • New South Wales, Australia · Boys

    In 2025, Leo was ranked #5 and Theo #32 among boys in New South Wales, Australia.

  • New Zealand · Boys

    In 2023, Leo was ranked #5 and Theo #19 among boys in New Zealand.

  • Northern Ireland · Boys

    In 2024, Leo was ranked #12 and Theo #5 among boys in Northern Ireland.

  • Republic of Ireland · Boys

    In 2025, Leo was ranked #10 and Theo #21 among boys in Republic of Ireland.

  • Norway · Boys

    In 2025, Leo was ranked #28 and Theo #22 among boys in Norway.

Leo and Theo over time

Leo and Theo appear together in 5 published lists, across 128 years of shared records. Leo held the stronger position in more years in 4 of them, Theo 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.

Theo reached its own highest recorded position earlier in 3 of those lists, Leo in 1. 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 2024, Theo moved ahead of Leo in Northern Ireland · Boys — #6 and #9 the year before became #12 and #5.

  • Repeatedly exchanged positions

    Leo and Theo changed places 4 times in Republic of Ireland · Boys between 1988 and 2025, ending at #10 and #21.

  • Closest over the longest run

    Across 29 shared years in England and Wales · Boys, Leo and Theo averaged 27.0 places apart, ending at #5 and #12.

  • Longest-running competitions

    Leo and Theo were both ranked in Norway · Boys for 36 years, from 1986 to 2025, ending at #28 and #22.

  • Peaked in the same years

    Both reached their highest recorded position in England and Wales · Boys within 2 years — Leo #5 in 2022, Theo #9 in 2022.

List by list

  • Norway · Boys36 shared years, 1986–2025

    Leo held the stronger position in 17 of those years, Theo in 19.

    Highest recorded here: Leo #28 in 2025, Theo #17 in 2024.

    The order changed in 2007: Theo moved ahead. In 2006 they stood at #77 and #85; by 2007 that had become #81 and #79.

    Most recent shared year, 2025: Leo #28, Theo #22.

  • Republic of Ireland · Boys30 shared years, 1988–2025

    Leo held the stronger position in 27 of those years, Theo in 3.

    Highest recorded here: Leo #10 in 2025, Theo #13 in 2024.

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

    Most recent shared year, 2025: Leo #10, Theo #21.

  • England and Wales · Boys29 shared years, 1996–2024

    Leo held the stronger position in 29 of those years, Theo in 0.

    Highest recorded here: Leo #5 in 2022, Theo #9 in 2022.

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

    Most recent shared year, 2024: Leo #5, Theo #12.

  • Northern Ireland · Boys23 shared years, 2001–2024

    Leo held the stronger position in 19 of those years, Theo in 4.

    Highest recorded here: Leo #6 in 2023, Theo #4 in 2022.

    The order changed in 2024: Theo moved ahead. In 2023 they stood at #6 and #9; by 2024 that had become #12 and #5.

    Most recent shared year, 2024: Leo #12, Theo #5.

  • New Zealand · Boys10 shared years, 2014–2023

    Leo held the stronger position in 10 of those years, Theo in 0.

    Highest recorded here: Leo #3 in 2019, Theo #19 in 2023.

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

    Most recent shared year, 2023: Leo #5, Theo #19.

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 Leo

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

Other comparisons involving Theo

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

  • Arthur vs Theo

    Arthur and Theo both rose over the same years in 5 registrars — England and Wales · Boys; New Zealand · Boys; Northern Ireland · Boys; Norway · Boys; Republic of Ireland · Boys. Each list is measured against its own starting position; the positions are never combined.

    Arthur · Theo · 37 shared years, 1986–2025 · Moved together in several countries

  • Henry vs Theo

    Henry and Theo both rose over the same years in 5 registrars — England and Wales · Boys; New Zealand · Boys; Northern Ireland · Boys; Norway · Boys; Republic of Ireland · Boys. Each list is measured against its own starting position; the positions are never combined.

    Henry · Theo · 37 shared years, 1986–2025 · Moved together in several countries

  • Theo vs Archie

    Theo and Archie both rose over the same years in 4 registrars — England and Wales · Boys; New Zealand · Boys; Northern Ireland · Boys; Republic of Ireland · Boys. Each list is measured against its own starting position; the positions are never combined.

    Theo · Archie · 30 shared years, 1996–2025 · Moved together in several countries

  • Theo vs Arlo

    Theo and Arlo both rose over the same years in 4 registrars — England and Wales · Boys; New Zealand · Boys; Northern Ireland · Boys; Republic of Ireland · Boys. Each list is measured against its own starting position; the positions are never combined.

    Theo · Arlo · 27 shared years, 1999–2025 · Moved together in several countries

Other pairs with the same kind of relationship

Pairs that qualify under the same rule as this one — one moved ahead of the other.

All one moved ahead of the other→

Other pairs from Northern Ireland lists

Pairs measured inside Northern Ireland's own published lists, where this pair's strongest relationship is also recorded. Positions in these lists are not comparable with another registrar's.

Northern Ireland overview→

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 Leo, Theo
FieldLeoTheo
Record typeEditorially researched profileEditorially researched profile
Gender usagemalemale
MeaningLion.Gift of God.
OriginLatinGreek, via Theodore/Theodora
Pronunciation/ˈliːoʊ//ˈθioʊ/
Syllables11
Common variants / nicknamesNot yet recordedTeddy
Recorded regional usageAU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NO, NZAU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NO, NZ
Most recent popularity observationNew South Wales, Australia · Boys #5 (2025)Republic of Ireland · Boys #21 (2025)
Pronunciation clarity (demonstration score)90/10090/100
Spelling simplicity (demonstration score)95/10095/100
International familiarity (demonstration score)100/100100/100
Data Confidencemediumhigh

What the data shows

  • Leo is recorded with a Latin origin, while Theo is recorded with a Greek, via Theodore/Theodora origin.
  • Leo and Theo both have 1 syllable.
  • Leo's recorded meaning differs from Theo'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 Leo a "medium" Data Confidence level and Theo a "high" level — this reflects how complete and corroborated the underlying evidence is, not a judgement of either name.

How each name got here

Leo

Popularity journey

  1. 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

  2. Highest recorded2009–2025

    Highest recorded position: #3 among boys in New South Wales, Australia, in 2022 (recorded 2009–2025).

    New South Wales, Australia · Boys

  3. Most recent2025

    Most recently recorded at #5 among boys in New South Wales, Australia, in 2025.

    New South Wales, Australia · Boys

Theo

Popularity journey

  1. First recorded1986

    First recorded at #637 among boys in Norway in 1986 — the earliest year that source publishes this name, not necessarily the earliest it was used.

    Norway · Boys

  2. Highest recorded2001–2024

    Highest recorded position: #4 among boys in Northern Ireland, in 2022 (recorded 2001–2024).

    Northern Ireland · Boys

  3. Most recent2025

    Most recently recorded at #32 among boys in New South Wales, Australia, in 2025.

    New South Wales, Australia · Boys