Claude 3 Opus vs GPT-5.1-Codex-Mini

Compare Claude 3 Opus by Anthropic against GPT-5.1-Codex-Mini by OpenAI, context windows of 200K vs 400K, tested across 12 shared challenges. Updated April 2026.

Which is better, Claude 3 Opus or GPT-5.1-Codex-Mini?

Claude 3 Opus and GPT-5.1-Codex-Mini are both competitive models. Claude 3 Opus costs $15/M input tokens vs $1.5/M for GPT-5.1-Codex-Mini. Context windows: 200K vs 400K tokens. Compare their real outputs side by side below.

Key Differences Between Claude 3 Opus and GPT-5.1-Codex-Mini

Claude 3 Opus is made by anthropic while GPT-5.1-Codex-Mini is from openai. Claude 3 Opus has a 200K token context window compared to GPT-5.1-Codex-Mini's 400K. On pricing, Claude 3 Opus costs $15/M input tokens vs $1.5/M for GPT-5.1-Codex-Mini.

Our Verdict
GPT-5.1-Codex-Mini
GPT-5.1-Codex-Mini
Claude 3 Opus
Claude 3 OpusRunner-up

No community votes yet. On paper, GPT-5.1-Codex-Mini has the edge — newer, bigger context window.

GPT-5.1-Codex-Mini is 13x cheaper per token — worth considering if cost matters.

Too close to call
Writing DNA

Style Comparison

Similarity
94%

GPT-5.1-Codex-Mini uses 332.9x more bold

Claude 3 Opus
GPT-5.1-Codex-Mini
54%Vocabulary65%
14wSentence Length20w
0.48Hedging0.56
0.0Bold3.3
3.0Lists3.4
0.00Emoji0.00
0.00Headings0.08
0.06Transitions0.05
Based on 3 + 13 text responses
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Claude 3 OpusGPT-5.1-Codex-Mini

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