Claude Haiku 4.5 vs Claude Opus 4.7 for Multilingual

What Multilingual requires: equivalent-quality output in non-English languages, robust preservation of meaning and tone, faithful translations, consistent persona across languages, and accurate classification/routing in local languages. Our primary measure for this task is the task score from our multilingual test: Claude Haiku 4.5 scores 5 and Claude Opus 4.7 scores 4 in our testing. Haiku's top task rank (rank 1 of 53) indicates it produces higher-quality non‑English outputs in our suite. Supporting signals: Haiku also scores 5 on faithfulness, 5 on persona consistency, 5 on tool calling, and 5 on long-context handling — all of which help deliver reliable multilingual responses, especially for preservation of nuance and context. Opus scores 5 on creative problem solving and 5 on long context, and scores 4 on constrained rewriting, indicating strengths for complex multilingual creative tasks or heavy-document workflows, but its multilingual score (4) and lower task rank (36 of 53) show it trails Haiku on straight multilingual fidelity in our tests.

Where Claude Haiku 4.5 shines (based on score differentials):

• Customer support localization: Haiku's 5/5 multilingual and 5/5 faithfulness produce more accurate, tone-preserving replies in Spanish, French, and Japanese while costing $1/ $5 per million tokens.
• Multilingual content pipelines: Haiku's persona consistency (5) and structured output (4) make it reliable for generating localized marketing copy that matches brand voice across languages.
• Large-context multilingual summarization: Haiku supports a 200k-token context window and scores 5 on long context, enabling accurate summaries of long foreign-language documents. Where Claude Opus 4.7 is useful (grounded in scores):
• Cross-lingual creative ideation: Opus scores 5 on creative problem solving, so for inventive multilingual campaign concepts or ideation in multiple languages it may produce more novel options despite a 4/5 multilingual score.
• Very large-document workflows: Opus offers a 1,000,000-token context window and massive max output (128k tokens), useful when you must process extremely long multi-language corpora; expect somewhat lower per-language fidelity compared to Haiku in our tests.
• Tight compression in multilingual transformation: Opus' 4/5 constrained rewriting helps when you must compress non-English text within strict size limits, though Haiku still leads on raw multilingual quality.

For Multilingual, choose Claude Haiku 4.5 if you prioritize highest equivalent-quality output in non‑English languages, faithfulness, persona consistency, and lower cost ($1 input / $5 output per million tokens) — Haiku scores 5 vs Opus 4 in our testing. Choose Claude Opus 4.7 if you need extreme context capacity (1,000,000-token window), stronger creative problem solving, or massive single-request outputs and you can accept slightly lower multilingual fidelity and higher cost ($5 input / $25 output per million tokens).