The 6 Celtic Languages and How They Compare

The Celtic language family once stretched from Ireland to Turkey. Today, six Celtic languages survive — all in the western fringes of Europe. Two have been revived from near-extinction. One has nearly a million speakers. Together, they represent one of the oldest and most distinctive branches of the Indo-European language family.

This guide covers all six: how they're related, how many speakers each has, what makes them distinctive, and how they compare to each other.

The Family Tree

The Celtic languages split into two main branches:

• Goidelic (also called Q-Celtic): Irish, Scottish Gaelic, and Manx
• Brythonic (also called P-Celtic): Welsh, Cornish, and Breton

The "Q" and "P" labels come from a key sound change: where Goidelic languages kept the original Proto-Celtic *kw- sound (written as "c" in modern spelling), Brythonic languages shifted it to "p." Compare:

Both branches share features that make them distinctively Celtic: initial consonant mutations, VSO word order, conjugated prepositions, and no single words for "yes" and "no."

Irish (Gaeilge)

Speakers: ~1.7 million with some ability, ~70,000-80,000 daily speakers outside education (Census 2022).<br/>Where: Republic of Ireland (official language), Northern Ireland, diaspora worldwide.<br/>Status: Official language of the Republic of Ireland and an official EU language. Protected in Northern Ireland. Three Gaeltacht (Irish-speaking) regions.

Irish is the most widely known Celtic language. It's taught in all schools in the Republic, has a dedicated TV channel (TG4), radio station (Raidió na Gaeltachta), and growing use in social media and daily life. Diaspora interest — particularly from the US, UK, and Australia — is at an all-time high. For a complete guide to learning Irish, see How to Learn Irish.

Welsh (Cymraeg)

Speakers: ~538,000 (Census 2021); ~880,000 (Annual Population Survey).<br/>Where: Wales, with small communities in Patagonia (Y Wladfa) and England.<br/>Status: Official language of Wales alongside English. Protected by law. Welsh Government target: one million speakers by 2050.

Welsh is the healthiest Celtic language in terms of community use and institutional support. Welsh-medium education is expanding, S4C broadcasts daily Welsh-language television, and an increasing number of employers require or prefer Welsh speakers. For a complete guide, see How to Learn Welsh.

Scottish Gaelic (Gàidhlig)

Speakers: ~57,000 (Census 2022).<br/>Where: Scottish Highlands and Islands, particularly the Outer Hebrides. Small communities in Glasgow, Edinburgh, and Nova Scotia.<br/>Status: Recognised by the Gaelic Language (Scotland) Act 2005. Supported by Bòrd na Gàidhlig. BBC ALBA broadcasts Gaelic-language television.

Scottish Gaelic is closely related to Irish — they shared a common literary language until roughly the 17th century. Today, there's moderate mutual intelligibility in writing but spoken conversation between the two is difficult without prior exposure. For a detailed comparison, see Irish vs Scottish Gaelic.

Breton (Brezhoneg)

Speakers: ~200,000 (estimates vary; declining).<br/>Where: Brittany (Breizh), northwest France.<br/>Status: No official recognition from the French state. Supported by regional organisations and Diwan immersion schools. Classified as "severely endangered" by UNESCO.

Breton is the only Celtic language spoken on the European continent. It's a Brythonic language — related to Welsh and Cornish, not to Irish. Breton was brought to Brittany by migrants from Britain in the 5th-6th centuries AD. Despite lacking official status in France, a strong revitalisation movement sustains Breton-medium education and media.

Cornish (Kernewek)

Speakers: ~500-3,500 (estimates vary widely).<br/>Where: Cornwall, southwest England.<br/>Status: Recognised under the European Charter for Regional or Minority Languages. Revived from extinction — the last traditional native speaker, Dolly Pentreath, died in 1777.

Cornish is a revival success story. After dying as a community language in the 18th century, it was gradually reconstructed from historical texts and revived through classes, immersion events, and a growing community of speakers. Several spelling standards exist (Kernewek Standard, Kernewek Kemmyn). It's the closest relative of Breton and has significant similarities with Welsh.

Manx (Gaelg)

Speakers: ~2,500 (mostly second-language).<br/>Where: Isle of Man.<br/>Status: Recognised as a regional language by the Isle of Man government. The Bunscoill Ghaelgagh (Manx-medium primary school) opened in 2001.

Manx is a Goidelic language — related to Irish and Scottish Gaelic. The last native speaker, Ned Maddrell, died in 1974. Since then, Manx has been revived through education and community efforts. Its spelling system is based on English conventions rather than the Gaelic system used by Irish and Scottish Gaelic, making it look quite different despite the close linguistic relationship.

How They Compare

Can They Understand Each Other?

Within branches: There's partial mutual intelligibility. Irish and Scottish Gaelic speakers can often understand each other's writing and get the gist of slow speech — roughly comparable to Spanish and Portuguese. Welsh and Cornish speakers have moderate mutual intelligibility. Breton and Welsh share vocabulary and grammar but have diverged enough that understanding takes effort.

Across branches: Very little. An Irish speaker and a Welsh speaker cannot understand each other — the two branches have been separated for at least 2,000 years. They share grammatical features (mutations, VSO order) but vocabulary and pronunciation have diverged too far.

Continental Celtic (Extinct)

The six living Celtic languages are the survivors of a much larger family. Continental Celtic languages — Gaulish (France, Belgium, northern Italy), Celtiberian (Spain), Galatian (central Turkey), and Lepontic (northern Italy) — all died out by roughly the 5th century AD, replaced by Latin and its descendants.

At their peak, Celtic languages were spoken across most of western and central Europe. The contraction to the Atlantic fringe was driven by Roman expansion, Germanic migration, and later by English and French linguistic dominance.

Which Celtic Language Should You Learn?

The practical answer depends on your connection and goals:

• Irish if you have Irish heritage, want the largest Goidelic community, or are interested in Irish culture, literature, and media.
• Welsh if you have Welsh connections, live in or plan to visit Wales, or want the Celtic language with the strongest community infrastructure and career relevance.
• Scottish Gaelic if you have Scottish connections or want to engage with Highland culture.
• Breton if you have Breton connections or are interested in the only continental Celtic language.
• Cornish or Manx if you have a connection to those communities or want to support a revival language.

If you have no specific connection, Irish or Welsh have the best learning resources, the largest communities, and the most media to practise with. blas. teaches both, and the grammar and mutation skills you learn in one Celtic language make learning a second one significantly easier.