_version_ 1866910195064504320
author Omnilingual MT Team
Alastruey, Belen
Bafna, Niyati
Caciolai, Andrea
Heffernan, Kevin
Kozhevnikov, Artyom
Ropers, Christophe
Sánchez, Eduardo
Saint-James, Charles-Eric
Tsiamas, Ioannis
Cao, Xiang "Tony"
Cheng, Chierh
Chuang, Joe
Duquenne, Paul-Ambroise
Duppenthaler, Mark
Ekberg, Nate
Gao, Cynthia
Cabot, Pere Lluís Huguet
Janeiro, João Maria
Maillard, Jean
Gonzalez, Gabriel Mejia
Schwenk, Holger
Toledo, Edan
Turkatenko, Arina
Ventayol-Boada, Albert
Moritz, Rashel
Mourachko, Alexandre
Parimi, Surya
Williamson, Mary
Yates, Shireen
Dale, David
Costa-jussà, Marta R.
author_facet Omnilingual MT Team
Alastruey, Belen
Bafna, Niyati
Caciolai, Andrea
Heffernan, Kevin
Kozhevnikov, Artyom
Ropers, Christophe
Sánchez, Eduardo
Saint-James, Charles-Eric
Tsiamas, Ioannis
Cao, Xiang "Tony"
Cheng, Chierh
Chuang, Joe
Duquenne, Paul-Ambroise
Duppenthaler, Mark
Ekberg, Nate
Gao, Cynthia
Cabot, Pere Lluís Huguet
Janeiro, João Maria
Maillard, Jean
Gonzalez, Gabriel Mejia
Schwenk, Holger
Toledo, Edan
Turkatenko, Arina
Ventayol-Boada, Albert
Moritz, Rashel
Mourachko, Alexandre
Parimi, Surya
Williamson, Mary
Yates, Shireen
Dale, David
Costa-jussà, Marta R.
contents High-quality machine translation (MT) can scale to hundreds of languages, setting a high bar for multilingual systems. However, compared to the world's 7,000 languages, current systems still offer only limited coverage: about 200 languages on the target side, and maybe a few hundreds more on the source side, supported due to cross-lingual transfer. And even these numbers have been hard to evaluate due to the lack of reliable benchmarks and metrics. We present Omnilingual Machine Translation (OMT), the first MT system supporting more than 1,600 languages. This scale is enabled by a comprehensive data strategy that integrates large public multilingual corpora with newly created datasets, including manually curated MeDLEY bitext. We explore two ways of specializing a Large Language model (LLM) for machine translation: as a decoder-only model (OMT-LLaMA) or as a module in an encoder-decoder architecture (OMT-NLLB). Notably, all our 1B to 8B parameter models match or exceed the MT performance of a 70B LLM baseline, revealing a clear specialization advantage and enabling strong translation quality in low-compute settings. Moreover, our evaluation of English-to-1,600 translations further shows that while baseline models can interpret undersupported languages, they frequently fail to generate them with meaningful fidelity; OMT-LLaMA models substantially expand the set of languages for which coherent generation is feasible. Additionally, OMT models improve in cross-lingual transfer, being close to solving the "understanding" part of the puzzle in MT for the 1,600 evaluated. Our leaderboard and main human-created evaluation datasets (BOUQuET and Met-BOUQuET) are dynamically evolving towards Omnilinguality and freely available.
format Preprint
id arxiv_https___arxiv_org_abs_2603_16309
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Omnilingual MT: Machine Translation for 1,600 Languages
Omnilingual MT Team
Alastruey, Belen
Bafna, Niyati
Caciolai, Andrea
Heffernan, Kevin
Kozhevnikov, Artyom
Ropers, Christophe
Sánchez, Eduardo
Saint-James, Charles-Eric
Tsiamas, Ioannis
Cao, Xiang "Tony"
Cheng, Chierh
Chuang, Joe
Duquenne, Paul-Ambroise
Duppenthaler, Mark
Ekberg, Nate
Gao, Cynthia
Cabot, Pere Lluís Huguet
Janeiro, João Maria
Maillard, Jean
Gonzalez, Gabriel Mejia
Schwenk, Holger
Toledo, Edan
Turkatenko, Arina
Ventayol-Boada, Albert
Moritz, Rashel
Mourachko, Alexandre
Parimi, Surya
Williamson, Mary
Yates, Shireen
Dale, David
Costa-jussà, Marta R.
Computation and Language
I.2.7
High-quality machine translation (MT) can scale to hundreds of languages, setting a high bar for multilingual systems. However, compared to the world's 7,000 languages, current systems still offer only limited coverage: about 200 languages on the target side, and maybe a few hundreds more on the source side, supported due to cross-lingual transfer. And even these numbers have been hard to evaluate due to the lack of reliable benchmarks and metrics. We present Omnilingual Machine Translation (OMT), the first MT system supporting more than 1,600 languages. This scale is enabled by a comprehensive data strategy that integrates large public multilingual corpora with newly created datasets, including manually curated MeDLEY bitext. We explore two ways of specializing a Large Language model (LLM) for machine translation: as a decoder-only model (OMT-LLaMA) or as a module in an encoder-decoder architecture (OMT-NLLB). Notably, all our 1B to 8B parameter models match or exceed the MT performance of a 70B LLM baseline, revealing a clear specialization advantage and enabling strong translation quality in low-compute settings. Moreover, our evaluation of English-to-1,600 translations further shows that while baseline models can interpret undersupported languages, they frequently fail to generate them with meaningful fidelity; OMT-LLaMA models substantially expand the set of languages for which coherent generation is feasible. Additionally, OMT models improve in cross-lingual transfer, being close to solving the "understanding" part of the puzzle in MT for the 1,600 evaluated. Our leaderboard and main human-created evaluation datasets (BOUQuET and Met-BOUQuET) are dynamically evolving towards Omnilinguality and freely available.
title Omnilingual MT: Machine Translation for 1,600 Languages
topic Computation and Language
I.2.7
url https://arxiv.org/abs/2603.16309