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Claude Haiku 4.5 vs GPT-5.1-Codex-Mini

Compare Claude Haiku 4.5 by Anthropic against GPT-5.1-Codex-Mini by OpenAI, in 193 community votes, claude haiku 4.5 wins 59% of head-to-head duels, context windows of 200K vs 400K, tested across 54 shared challenges. Updated April 2026.

Which is better, Claude Haiku 4.5 or GPT-5.1-Codex-Mini?

Claude Haiku 4.5 is the better choice overall, winning 59% of 193 blind community votes on Rival. Claude Haiku 4.5 costs $1/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 Haiku 4.5 and GPT-5.1-Codex-Mini

Claude Haiku 4.5 is made by anthropic while GPT-5.1-Codex-Mini is from openai. Claude Haiku 4.5 has a 200K token context window compared to GPT-5.1-Codex-Mini's 400K. On pricing, Claude Haiku 4.5 costs $1/M input tokens vs $1.5/M for GPT-5.1-Codex-Mini. In community voting, In 193 community votes, Claude Haiku 4.5 wins 59% of head-to-head duels.

In 193 community votes, Claude Haiku 4.5 wins 59% of head-to-head duels. Claude Haiku 4.5 leads in Image Generation, Analysis, Conversation, while GPT-5.1-Codex-Mini leads in Reasoning. Based on blind community voting from the Rival open dataset of 193+ human preference judgments for this pair.

Reasoning: GPT-5.1-Codex-Mini wins 57% of votes
Web Design: Claude Haiku 4.5 and GPT-5.1-Codex-Mini are tied
Image Generation: Claude Haiku 4.5 wins 90% of votes
Analysis: Claude Haiku 4.5 wins 67% of votes
Conversation: Claude Haiku 4.5 wins 57% of votes
Our Verdict
Claude Haiku 4.5
Claude Haiku 4.5Winner
GPT-5.1-Codex-Mini
GPT-5.1-Codex-MiniRunner-up

Pick Claude Haiku 4.5. In 193 blind votes, Claude Haiku 4.5 wins 59% of the time. That's not luck.

Pick Claude Haiku 4.5 for Image Generation, Analysis, Conversation. Pick GPT-5.1-Codex-Mini for Reasoning.

Clear winner
Writing DNA

Style Comparison

Similarity
98%

Claude Haiku 4.5 uses 20.4x more emoji

Claude Haiku 4.5
GPT-5.1-Codex-Mini
61%Vocabulary65%
47wSentence Length20w
0.64Hedging0.56
5.1Bold3.3
6.3Lists3.4
0.20Emoji0.00
2.46Headings0.08
0.17Transitions0.05
Based on 24 + 13 text responses
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Claude Haiku 4.5GPT-5.1-Codex-Mini

279 AI models invented the same fake scientist.

We read every word. 250 models. 2.14 million words. This is what we found.

AI Hallucination Index 2026
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