Claude 3 Opus vs OpenAI o3

Compare Claude 3 Opus by Anthropic against OpenAI o3 by OpenAI, tested across 12 shared challenges. Updated April 2026.

Which is better, Claude 3 Opus or OpenAI o3?

Claude 3 Opus and OpenAI o3 are both competitive models. Claude 3 Opus costs $15/M input tokens vs $10/M for OpenAI o3. Compare their real outputs side by side below.

Key Differences Between Claude 3 Opus and OpenAI o3

Claude 3 Opus is made by anthropic while OpenAI o3 is from openai. On pricing, Claude 3 Opus costs $15/M input tokens vs $10/M for OpenAI o3.

Our Verdict
Claude 3 Opus
Claude 3 Opus
OpenAI o3
OpenAI o3

No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.

Too close to call
Writing DNA

Style Comparison

Similarity
98%

OpenAI o3 uses 69.5x more bold

Claude 3 Opus
OpenAI o3
54%Vocabulary68%
14wSentence Length14w
0.48Hedging0.26
0.0Bold0.7
3.0Lists3.0
0.00Emoji0.00
0.00Headings0.38
0.06Transitions0.12
Based on 3 + 16 text responses
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Ask them anything yourself

Claude 3 OpusOpenAI o3

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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