ChatGPT-4o (March 2025) vs GPT-5 Pro

Compare ChatGPT-4o (March 2025) and GPT-5 Pro, both from OpenAI, context windows of 128K vs 400K, tested across 28 shared challenges. Updated April 2026.

Which is better, ChatGPT-4o (March 2025) or GPT-5 Pro?

ChatGPT-4o (March 2025) and GPT-5 Pro are both competitive models. ChatGPT-4o (March 2025) costs $5/M input tokens vs $15/M for GPT-5 Pro. Context windows: 128K vs 400K tokens. Compare their real outputs side by side below.

Key Differences Between ChatGPT-4o (March 2025) and GPT-5 Pro

ChatGPT-4o (March 2025) is made by openai while GPT-5 Pro is from openai. ChatGPT-4o (March 2025) has a 128K token context window compared to GPT-5 Pro's 400K. On pricing, ChatGPT-4o (March 2025) costs $5/M input tokens vs $15/M for GPT-5 Pro.

Our Verdict
GPT-5 Pro
GPT-5 Pro
ChatGPT-4o (March 2025)
ChatGPT-4o (March 2025)Runner-up

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

ChatGPT-4o (March 2025) is 8.0x cheaper per token — worth considering if cost matters.

Too close to call
Writing DNA

Style Comparison

Similarity
91%

ChatGPT-4o (March 2025) uses 329.7x more bold

ChatGPT-4o (March 2025)
GPT-5 Pro
55%Vocabulary65%
24wSentence Length15w
0.52Hedging0.32
3.3Bold0.0
6.0Lists2.9
0.94Emoji0.00
0.63Headings0.00
0.05Transitions0.01
Based on 15 + 11 text responses
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ChatGPT-4o (March 2025)GPT-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
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