Anthropic has updated its intermediate-tier AI model, Sonnet, just two weeks after the release of its flagship Opus 4.6. Sonnet 4.6 is now the default model for users on both the Free and Pro plans.
The update, delivered on a quarterly cycle, focuses on improvements in three key areas: coding, instruction following, and computer usage. These enhancements are strategically aligned with the competitive landscape for mid-range AI models – those increasingly utilized by businesses for everyday tasks – and will be crucial in determining which services offer the best value.
Anthropic Launches Claude Sonnet 4.6: More Powerful with a Massive Context Window
A significant upgrade is the expanded context window, which, in beta testing, has doubled to reach one million tokens. According to Anthropic, this capacity is sufficient to handle entire codebases, lengthy contracts, or dozens of research papers within a single prompt. This allows users to submit complete projects at once, rather than breaking them down into smaller parts.
While a one million token context window isn’t entirely new – Gemini has offered similar capabilities for some time – it represents a substantial advancement for Sonnet, the model most frequently used by Claude customers. This expanded capacity could significantly improve workflow efficiency for developers and researchers.
Benchmark Results: Impressive Numbers
Sonnet 4.6 has achieved leading scores in several benchmark tests, including top results on OS World for computer usage and SWE-Bench for software engineering. Notably, the model scored 60.4% on ARC-AGI-2, a test designed to measure human-level intelligence capabilities, placing Sonnet 4.6 above the majority of other models.
However, it still trails more powerful and expensive models like Opus 4.6, Gemini 3 Deep Think, and an optimized version of GPT 5.2, a result that was anticipated for a mid-range model. Sonnet is designed to provide the optimal balance between performance and cost, and the data suggests It’s succeeding in that goal.
The next step for Anthropic is an update to Haiku, the smallest and fastest model in the Claude family, which is expected in the coming weeks.
