Claude 3.5 Sonnet vs Claude Sonnet 4.6

Claude 3.5 Sonnet

Anthropic

Claude 3.5 Sonnet, updated by Anthropic in October 2024 (originally released June 2024), is a large language model from the Claude 3.5 family that delivered strong performance in coding, reasoning, and instruction-following at its release. It supports a 200K token context window, 8K maximum output tokens, and native image understanding including screenshot analysis and document comprehension. Claude 3.5 Sonnet targets general-purpose development tasks, document analysis, and applications requiring reliable instruction following with visual input support.

Claude Sonnet 4.6

Anthropic

Claude Sonnet 4.6 is a general-purpose language model from Anthropic, released in February 2026 as an update to the Sonnet 4 line that introduced adaptive thinking — a mode where the model automatically calibrates its reasoning depth based on task complexity rather than requiring manual configuration by the developer. The model accepts text and image inputs and integrates natively with web search and code execution tools, consolidating capabilities that previously required separate toolchain setup into a unified API surface. It became the primary workhorse model in the Claude 4 series for code assistance, agentic pipelines, and retrieval-augmented applications that benefit from built-in web access.