Anthropic is upgrading Claude Sonnet, replacing Sonnet 4.6 from February with Sonnet 5 as the best medium-sized model.
Claude Sonnet 5 has arrived as ‘most agentic Sonnet model yet’
In Anthropic’s universe, Sonnet is Claude’s medium-sized AI model that sits between the smaller Haiku model and the larger Opus model.
“Claude Sonnet 5 is built to be the most agentic Sonnet model yet. It can make plans, use tools like browsers and terminals, and run autonomously at a level that, just a few months ago, required larger and more expensive models,” the company says.
“Sonnet 5 narrows the gap: its performance is close to that of Opus 4.8, but at lower prices. It’s a substantial improvement over its predecessor, Sonnet 4.6, on important aspects of agentic performance like reasoning, tool use, coding, and knowledge work.”
Sonnet 5 is the new default model for Claude free and pro users
Anthropic says that today’s Sonnet 5 release is the default for both Free and Pro Claude users. The company also has special introductory pricing that runs through August 31.
“Claude Sonnet 5 is available everywhere today at an introductory price of $2 per million input tokens and $10 per million output tokens through August 31, 2026,” the company says.
“It then moves to standard pricing at $3 per million input tokens and $15 per million output tokens. We’ve increased rate limits across Chat, Cowork, Claude Code, and the Claude Platform to accommodate the higher token usage of higher effort levels; users can select whichever level makes sense for their particular project,” Anthropic adds.
Anthropic also has its most capable Mythos 5 and Fable 5 models. Mythos 5 has fewer guardrails for select security researchers and platform owners.
Fable 5 is the safer version that was briefly available for customers before being blocked by the U.S. government. Anthropic says it’s working on restoring access in the future.
Claude Opus 4.8 arrived at the end of May. Claude Fable 5 followed a few days later before being pulled. Mythos 5 has partially been restored to select customers.
Claude Sonnet 5 arrives four months after the previous Sonnet 4.6 release. You can learn more about Claude Sonnet 5 here.
Earlier today, Anthropic also released a brand-new desktop app with Claude Science for Mac and Linux.
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