Claude 3 Opus vs o1

Compare Claude 3 Opus by Anthropic against o1 by OpenAI, context windows of 200K vs 128K, tested across 12 shared challenges. Updated April 2026.

Which is better, Claude 3 Opus or o1?

Claude 3 Opus and o1 are both competitive models. Claude 3 Opus costs $15/M input tokens vs $15/M for o1. Context windows: 200K vs 128K tokens. Compare their real outputs side by side below.

Key Differences Between Claude 3 Opus and o1

Claude 3 Opus is made by anthropic while o1 is from openai. Claude 3 Opus has a 200K token context window compared to o1's 128K. On pricing, Claude 3 Opus costs $15/M input tokens vs $15/M for o1.

Our Verdict
Claude 3 Opus
Claude 3 Opus
o1
o1Runner-up

No community votes yet. On paper, Claude 3 Opus has the edge — bigger model tier, bigger context window.

Too close to call
Writing DNA

Style Comparison

Similarity
98%

o1 uses 503.7x more bold

Claude 3 Opus
o1
54%Vocabulary64%
14wSentence Length16w
0.48Hedging0.76
0.0Bold5.0
3.0Lists2.6
0.00Emoji0.00
0.00Headings0.44
0.06Transitions0.40
Based on 3 + 13 text responses
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Claude 3 Opuso1

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
Free preview13 of 58 slides
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