Namewise

Isla vs Thea

Isla and Theacompared 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 · Girls

    In 2023, Isla was ranked #1 and Thea #95 among girls in New South Wales, Australia.

  • Scotland · Girls

    In 2024, Isla was ranked #2 and Thea #65 among girls in Scotland.

  • New Zealand · Girls

    In 2023, Isla was ranked #3 and Thea #70 among girls in New Zealand.

  • England and Wales · Girls

    In 2025, Isla was ranked #4 and Thea #66 among girls in England and Wales.

  • Northern Ireland · Girls

    In 2024, Isla was ranked #8 and Thea #75 among girls in Northern Ireland.

  • Republic of Ireland · Girls

    In 2025, Isla was ranked #13 and Thea #207 among girls in Republic of Ireland.

Isla and Thea over time

Isla and Thea appear together in 4 published lists, across 81 years of shared records. Isla held the stronger position in more years in 4 of them, Thea in 0.

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.

Thea reached its own highest recorded position earlier in 3 of those lists, Isla 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.

  • Repeatedly exchanged positions

    Isla and Thea changed places 4 times in England and Wales · Girls between 1996 and 2025, ending at #4 and #66.

  • Longest-running competitions

    Isla and Thea were both ranked in England and Wales · Girls for 30 years, from 1996 to 2025, ending at #4 and #66.

  • Peaked in the same years

    Both reached their highest recorded position in New Zealand · Girls within 2 years — Isla #1 in 2020, Thea #31 in 2019.

List by list

  • England and Wales · Girls30 shared years, 1996–2025

    Isla held the stronger position in 27 of those years, Thea in 3.

    Highest recorded here: Isla #3 in 2014, Thea #46 in 2019.

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

    Most recent shared year, 2025: Isla #4, Thea #66.

  • Republic of Ireland · Girls22 shared years, 2002–2025

    Isla held the stronger position in 20 of those years, Thea in 1.

    Highest recorded here: Isla #11 in 2023, Thea #136 in 2021.

    The order changed in 2006: Isla moved ahead. In 2005 they stood at #587 and #523; by 2006 that had become #394 and #464.

    Most recent shared year, 2025: Isla #13, Thea #207.

  • Northern Ireland · Girls19 shared years, 2004–2024

    Isla held the stronger position in 18 of those years, Thea in 0.

    Highest recorded here: Isla #1 in 2023, Thea #40 in 2019.

    The order changed in 2005: Isla moved ahead. In 2004 they stood at #372 and #372; by 2005 that had become #278 and #377.

    Most recent shared year, 2024: Isla #8, Thea #75.

  • New Zealand · Girls10 shared years, 2014–2023

    Isla held the stronger position in 10 of those years, Thea in 0.

    Highest recorded here: Isla #1 in 2020, Thea #31 in 2019.

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

    Most recent shared year, 2023: Isla #3, Thea #70.

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 Isla

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

Other comparisons involving Thea

Pairs where Thea 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 — peaked in the same years.

All peaked in the same years→

Other pairs from New Zealand lists

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

New Zealand 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 Isla, Thea
FieldIslaThea
Record typeEditorially researched profileEditorially researched profile
Gender usagefemalefemale
MeaningA Scottish place name; not generally treated as having a separate lexical 'meaning' beyond the river/place it names.A short form of Dorothea, Theodora, Theresa and other similar-sounding Greek-rooted names.
OriginScottishGreek (via Germanic/Scandinavian transmission)
Pronunciation/ˈaɪlə//ˈteː.a/
Syllables21
Common variants / nicknamesIslayNot yet recorded
Recorded regional usageAU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NZAU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NO, NZ
Most recent popularity observationEngland and Wales · Girls #4 (2025)Norway · Girls #50 (2025)
Pronunciation clarity (demonstration score)90/10090/100
Spelling simplicity (demonstration score)95/10095/100
International familiarity (demonstration score)100/100100/100
Data Confidencehighmedium

What the data shows

  • Isla is recorded with a Scottish origin, while Thea is recorded with a Greek (via Germanic/Scandinavian transmission) origin.
  • Isla has 2 syllables, compared with 1 for Thea.
  • Isla's recorded meaning differs from Thea's — see the table above for each.
  • Both names have recorded usage in AU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NZ.
  • The available evidence gives Isla a "high" Data Confidence level and Thea a "medium" level — this reflects how complete and corroborated the underlying evidence is, not a judgement of either name.

How each name got here

Isla

Popularity journey

  1. First recorded1979

    First recorded at #467 among girls in Republic of Ireland in 1979 — the earliest year that source publishes this name, not necessarily the earliest it was used.

    Republic of Ireland · Girls

  2. Highest recorded2008–2025

    Highest recorded position: #1 among girls in New South Wales, Australia, in 2023 (recorded 2008–2025).

    New South Wales, Australia · Girls

  3. Most recent2025

    Most recently recorded at #4 among girls in England and Wales, in 2025.

    England and Wales · Girls

Thea

Popularity journey

  1. First recorded1950

    First recorded at #380 among girls in Norway in 1950 — the earliest year that source publishes this name, not necessarily the earliest it was used.

    Norway · Girls

  2. Highest recorded1950–2025

    Highest recorded position: #1 among girls in Norway, in 2006 (recorded 1950–2025).

    Norway · Girls

  3. Most recent2025

    Most recently recorded at #66 among girls in England and Wales, in 2025.

    England and Wales · Girls