English to Basque: AI Translation Comparison
English to Basque: AI Translation Comparison
Basque (Euskara) is spoken by approximately 750,000 people in the Basque Country spanning northeastern Spain and southwestern France, with small diaspora communities in the Americas. Basque is a language isolate with no known relatives, making it one of the most linguistically distinctive languages in Europe. It is ergative-absolutive (unlike the nominative-accusative pattern of most European languages), agglutinative with extensive suffixation, uses SOV word order, and has a complex auxiliary verb system that agrees with subject, direct object, and indirect object simultaneously. Translation demand comes from the Basque autonomous government, education (Basque-medium schools), media, cultural preservation, and tourism.
This comparison evaluates five leading AI translation systems on English-to-Basque accuracy, naturalness, and suitability for different use cases.
Translation comparisons are based on automated metrics and editorial evaluation. Quality varies by language pair and content type.
Accuracy Comparison Table
| System | BLEU Score | COMET Score | Editorial Rating (1-10) | Best For |
|---|---|---|---|---|
| Google Translate | 22.7 | 0.768 | 5.5 | General-purpose, free access |
| DeepL | 24.3 | 0.781 | 5.8 | Basic formal content |
| GPT-4 | 25.8 | 0.794 | 6.2 | Contextual accuracy |
| Claude | 23.4 | 0.773 | 5.6 | Long-form content |
| NLLB-200 | 24.1 | 0.779 | 5.9 | Strong for an isolate, self-hosted |
Translation Quality Metrics: BLEU, COMET, and Human Evaluation Explained
Example Translations
Formal Business Email
Source: “We are pleased to inform you that the Basque Government has approved funding for your research project. The grant terms are detailed in the attached agreement.”
| System | Translation |
|---|---|
| Pozik gaude jakinarazten zure ikerketa proiektua finantzatzeko Eusko Jaurlaritzak onarpena eman duela. Dirulaguntzaren baldintzak erantsitako hitzarmenean zehazten dira. | |
| DeepL | Atsegin handiz jakinarazten dizugu Eusko Jaurlaritzak zure ikerketa-proiekturako finantzaketa onartu duela. Dirulaguntzaren baldintzak erantsitako hitzarmenean xehatzen dira. |
| GPT-4 | Pozik gaude jakinarazten dizugu Eusko Jaurlaritzak zure ikerketa-proiektua finantzatzeko diru-laguntza onartu duela. Diru-laguntzaren baldintzak erantsitako akordioan zehazturik daude. |
| Claude | Pozik gaude jakinarazten Eusko Jaurlaritzak zure ikerketa proiekturako finantzaketa onartu duela. Dirulaguntzaren baldintzak erantsitako hitzarmenean zehazten dira. |
| NLLB-200 | Pozik gaude jakinarazten zure ikerketa-proiektua finantzatzeko Eusko Jaurlaritzak diru-laguntza onartu duela. Diru-laguntzaren baldintzak erantsitako hitzarmenean zehazten dira. |
Assessment: DeepL correctly includes the indirect object agreement “dizugu” (we inform you) in the verb form, which is essential in Basque. GPT-4 also includes this form. Claude and Google omit the dative agreement, producing a grammatically incomplete sentence. GPT-4’s “zehazturik daude” (are detailed) uses the resultative participle, which is more natural than “zehazten dira” (are being detailed) for a static description. All systems correctly use “Eusko Jaurlaritza” (Basque Government).
Casual Conversation
Source: “Want to go surfing at Mundaka this weekend? The waves are supposed to be huge. We could get pintxos after.”
| System | Translation |
|---|---|
| Surf egitera joan nahi duzu Mundakara asteburuan? Olatuak handiak izango direla esaten dute. Pintxoak jan genitzake gero. | |
| DeepL | Mundakara surf egitera joan nahi al duzu asteburuan? Olatuak handiak izango omen dira. Gero pintxoak jan genitzake. |
| GPT-4 | Mundakan surfa egitera joan nahi duzu asteburu honetan? Olatu handiak egongo omen dira. Gero pintxoak hartu genitzake. |
| Claude | Surf egitera joan nahi duzu Mundakara asteburuan? Olatuak handiak izango direla esaten dute. Pintxoak jan genitzake gero. |
| NLLB-200 | Mundakara surf egitera joan nahi duzu asteburuan? Olatuak handiak izango dira. Pintxoak jan genitzake gero. |
Assessment: DeepL and GPT-4 correctly use “omen” (the Basque reportative evidential particle, meaning “supposedly/reportedly”), which precisely translates “supposed to be.” GPT-4’s “pintxoak hartu” (grab pintxos) is more colloquial than “pintxoak jan” (eat pintxos). DeepL adds the question particle “al” for a more natural interrogative. The ergative-absolutive case marking is handled correctly by all systems for this simple sentence, but complexity increases with longer constructions.
Technical Content
Source: “The cooperative’s management platform integrates supply chain tracking with member voting systems to enable democratic governance of production decisions.”
| System | Translation |
|---|---|
| Kooperatibaren kudeaketa-plataformak hornidura-katearen jarraipena integratzen du kideen botazio-sistemekin, ekoizpen-erabakien gobernu demokratikoa ahalbidetzeko. | |
| DeepL | Kooperatibaren kudeaketa-plataformak hornidura-katearen jarraipena eta kideen bozketa-sistemak integratzen ditu, ekoizpen-erabakien gobernantzademokratikoa ahalbidetzeko. |
| GPT-4 | Kooperatibaren kudeaketa-plataformak hornidura-katearen jarraipena eta kideen bozketa-sistemak bateratzen ditu, ekoizpen-erabakien gobernantza demokratikoa ahalbidetzeko. |
| Claude | Kooperatibaren kudeaketa-plataformak hornidura-katearen jarraipena integratzen du kideen botazio-sistemekin, ekoizpen-erabakien gobernu demokratikoa ahalbidetzeko. |
| NLLB-200 | Kooperatibaren kudeaketa-plataformak hornidura-katearen jarraipena integratzen du kideen bozketa-sistemekin, ekoizpen-erabakien gobernantzademokratikoa ahalbidetzeko. |
Assessment: GPT-4 uses “bateratzen ditu” (combines them, with plural absolutive agreement) rather than “integratzen du” (integrates it, singular), correctly recognizing that two things are being integrated. This demonstrates proper Basque verb agreement. GPT-4 also uses “gobernantza demokratikoa” (democratic governance) with correct spacing, while NLLB-200 merges them. Basque cooperative terminology is well-established due to the Mondragon cooperative tradition. Best Translation AI for Technical Documentation
Strengths and Weaknesses
Google Translate
Strengths: Free and accessible. Basque Government corpus data improves quality. Basic sentence structure. Weaknesses: Frequent verb agreement errors (subject-object-indirect object). Often misses ergative case marking. Word order problems.
DeepL
Strengths: Better than Google for formal content. Good use of evidential particles. Reasonable vocabulary. Weaknesses: Premium pricing. Verb agreement errors in complex sentences. Limited idiomatic Basque.
GPT-4
Strengths: Best overall quality. Best verb agreement handling. Good cultural context. Understands cooperative terminology. Weaknesses: Higher cost. Sometimes generates Spanish-influenced constructions. Occasional dialect mixing.
Claude
Strengths: Consistent quality for long documents. Reasonable formal register. Weaknesses: Frequent verb agreement omissions. Limited Basque-specific knowledge. Similar quality to Google.
NLLB-200
Strengths: Surprisingly competitive for a language isolate. Free and self-hosted. Meta’s focus on low-resource languages benefits Basque. Weaknesses: Verb agreement errors. Formatting issues (merged words). Limited vocabulary depth.
Recommendations
| Use Case | Recommended System |
|---|---|
| Government / institutional | GPT-4 with human review |
| Education materials | GPT-4 or NLLB-200 with review |
| Tourism content | GPT-4 |
| Cooperative / business | GPT-4 |
| High-volume, cost-sensitive | NLLB-200 (self-hosted) |
| Quick personal translation | Google Translate (free) |
| Long-form content | Claude with review |
Best Translation AI in 2026: Complete Model Comparison
Key Takeaways
- GPT-4 leads for English-to-Basque with the best verb agreement handling, but all systems produce noticeable errors. Human review remains essential for any published Basque content.
- Basque’s ergative-absolutive alignment and polypersonal verb agreement (where the auxiliary verb agrees with up to three arguments simultaneously) are the primary challenges, and no AI system handles them reliably in complex sentences.
- NLLB-200 is notably competitive for Basque, benefiting from Meta’s deliberate focus on underrepresented languages, and offers a cost-effective baseline for organizations with Basque translation needs.
- The Basque Government’s strong language policy creates institutional demand and parallel corpus data, but Basque’s status as an isolate means AI systems cannot leverage related-language transfer learning.
Next Steps
- Try it yourself: Compare these systems on your own text in the Translation AI Playground: Compare Models Side-by-Side.
- Low-resource languages: Learn more in Low-Resource Languages: Where NLLB and Aya Shine.
- Check the leaderboard: Browse our full Translation Accuracy Leaderboard by Language Pair.
- Full model comparison: Read Best Translation AI in 2026: Complete Model Comparison.