From the archive
Claude Sonnet 4 now supports 1M tokens of context
Anthropic adds a 1M-token context window to Claude Sonnet 4, enabling whole-codebase analysis, large document synthesis, and more.
By Chat Overview
Published
Updated
Anthropic introduced a one-million-token context window for Claude Sonnet 4 in August 2025. The public beta started on its API and Amazon Bedrock; Google Cloud Vertex AI support followed on August 26.
What a larger context window allows
- Include more files when analyzing a codebase.
- Work with longer documents or collections of documents in one request.
- Retain more conversation and tool results during a multi-step task.
Longer input does not guarantee that every detail will appear correctly in the answer. For large document tasks, check the important findings against the original material.
Costs and current availability
At launch, prompts above 200,000 tokens had a different pricing tier. Prompt caching and batch processing offered ways to reduce some usage costs. For today's models and prices, see the Anthropic profile .