Anthropic launches Claude Sonnet 5 as default model

Anthropic released Claude Sonnet 5 on Tuesday, making it the new default model across Free, Pro, Max, Team, and Enterprise plans. The model replaces Sonnet 4.6 and is designed to deliver near-flagship performance at a fraction of the cost of the company's top-tier Opus 4.8 model.

Pricing and Availability

Sonnet 5 launches with introductory pricing of $2 per million input tokens and $10 per million output tokens through August 31, 2026, after which it will move to standard pricing of $3 per million input tokens and $15 per million output tokens. The model is available immediately through the Claude API, Claude Code, and all subscription tiers.9to5mac+1

"Testers described how it finishes complex tasks where previous Sonnets would stop short, how it checks its own output without explicitly being asked, and how it does all this agentic work at an attractive price point," Anthropic said in a statement.finance.yahoo

Agentic Capabilities and Performance

The release centers on improved autonomous capabilities. Sonnet 5 can plan and execute multi-step tasks, use web browsers and terminals independently, and complete projects that previously required more expensive models. Anthropic says the model closes the performance gap with Opus 4.8 while costing less than half as much on input tokens.testingcatalog+1

The company has also increased rate limits across Chat, Cowork, Claude Code, and the Claude Platform to accommodate higher token usage at elevated effort levels.9to5mac

Safety and Reliability

Anthropic emphasized safety improvements in this release, noting that Sonnet 5 scores lower on undesirable behaviors compared to earlier Sonnet versions. The model has been deployed with real-time cybersecurity safeguards similar to those used in Opus-class models, despite not being specifically trained for cybersecurity tasks.finance.yahoo+1

The launch comes as Anthropic continues to ship models at a rapid pace in 2026, having released Opus 4.8 in late May and the higher-end Fable 5 and Mythos 5 models earlier in June. Sonnet 5 positions itself as the workhorse option for developers and everyday users seeking capable agentic AI without premium pricing.metacto+1