Claude 3 Opus vs GPT-5 Pro

Compare Claude 3 Opus by Anthropic against GPT-5 Pro by OpenAI, context windows of 200K vs 400K, tested across 8 shared challenges. Updated April 2026.

Which is better, Claude 3 Opus or GPT-5 Pro?

Claude 3 Opus and GPT-5 Pro are both competitive models. Claude 3 Opus costs $15/M input tokens vs $15/M for GPT-5 Pro. Context windows: 200K vs 400K tokens. Compare their real outputs side by side below.

Key Differences Between Claude 3 Opus and GPT-5 Pro

Claude 3 Opus is made by anthropic while GPT-5 Pro is from openai. Claude 3 Opus has a 200K token context window compared to GPT-5 Pro's 400K. On pricing, Claude 3 Opus costs $15/M input tokens vs $15/M for GPT-5 Pro.

Our Verdict
GPT-5 Pro
GPT-5 Pro
Claude 3 Opus
Claude 3 OpusRunner-up

No community votes yet. On paper, GPT-5 Pro has the edge — newer, bigger context window.

Too close to call
Writing DNA

Style Comparison

Similarity
99%

Claude 3 Opus uses 5.6x more transitions

Claude 3 Opus
GPT-5 Pro
54%Vocabulary65%
14wSentence Length15w
0.48Hedging0.32
0.0Bold0.0
3.0Lists2.9
0.00Emoji0.00
0.00Headings0.00
0.06Transitions0.01
Based on 3 + 11 text responses
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Claude 3 OpusGPT-5 Pro

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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