Context Window

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GPT-5.1-Codex vs Jp Anthropic Claude Sonnet 4 6

This page is context-first: how much text each model can take in one request. Full specs adds capabilities and limits; the pricing matrix below is only about $/million tokens from hosts that list both models.

Openai

Model

GPT-5.1-Codex

Image inputTool calling

Context window

400K

400,000 tokens · ~300K words

Model page
Anthropic

Model

Jp Anthropic Claude Sonnet 4 6

Image inputTool calling

Context window

1M

1,000,000 tokens · ~750K words

Model page

Context window · side by side

Bar length is relative to the larger of the two windows (100% = max of this pair). This is not pricing.

GPT-5.1-Codex400K
Jp Anthropic Claude Sonnet 4 61M

Jp Anthropic Claude Sonnet 4 6 has about 2.5× the context window of the other in this pair.

Token calculator →Memory savings →

Jp Anthropic Claude Sonnet 4 6 has 150% more context capacity (1000K vs 400K tokens).

Quick verdicts

Short takeaways — validate with your own workloads.

  • Long document processing

    Use Jp Anthropic Claude Sonnet 4 6. Its 1000K context fits entire documents without chunking (vs 400K).

  • Long output (reports, code files)

    Use GPT-5.1-Codex. Its 128K max output lets you generate complete artifacts in one request.

Full specs

Context, output, capabilities, and dates. Green highlights the favorable value where we compute a winner.

SpecGPT-5.1-CodexJp Anthropic Claude Sonnet 4 6
Context window400,000 tokens (400K)1,000,000 tokens (1000K)
Max output tokens128,000 tokens (128K)64,000 tokens (64K)
Speed tierBalancedBalanced
VisionYesYes
Function callingYesYes
Extended thinkingYesYes
Prompt cachingYesYes
Batch APINoYes
Release dateNov 2025N/A

Pricing matrix

Dollar rates only: hosts that list both models, per 1M tokens. For how much text fits, use the context section above — not this table.

ProviderGPT-5.1-Codex inGPT-5.1-Codex outJp Anthropic Claude Sonnet 4 6 inJp Anthropic Claude Sonnet 4 6 out
Aws Bedrock——$3.30/M$16.50/M

Frequently asked questions

Jp Anthropic Claude Sonnet 4 6 has a larger context window: 1000K tokens vs 400K. For long documents, large codebases, or extended agent sessions, the larger context window reduces the need to chunk inputs or summarize history.

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Without Mem0~128K tokens sent
Full history
Repeated info
Old context
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