Anthropic said on Monday it has launched its mid-range model, Claude Sonnet 5.

The company said Sonnet 5 offers performance close to Opus 4.8 while being cheaper to use.

It will be applied as the default model for Claude Free and Pro plans and will be available across all subscription tiers.

Through Aug. 31, pricing is $2 per 1 million input tokens and $10 per 1 million output tokens. After that, only the input price rises to $3. It is cheaper than Opus 4.8, OpenAI's GPT-5.5 and Google's Gemini 3.1 Pro. It is more expensive than Gemini 3.5 Flash.

TechCrunch reported that Sonnet 5 has significantly improved reasoning, tool use, coding and knowledge-work performance compared with Sonnet 4.6 released in February. In one benchmark, Sonnet 5 scored 63.2 percent on autonomous coding. Opus 4.8 scored 69.2 percent and Sonnet 4.6 scored 58.1 percent. In a knowledge-work benchmark, Sonnet 5 slightly outperformed Opus 4.8.

Anthropic explained, "Opus 4.8 is still suitable for tasks that require higher accuracy," while adding, "Sonnet 5 provides high quality at a lower price."

Daniel Shepherd (대니얼 셰퍼드), a senior engineer at Zapier, said, "I assigned two tasks at once — updating Salesforce customer tiers and sending enterprise customers news of the launch — and it handled them to the end without stopping in the middle," adding, "It would have stopped midway before."