Gemini 2.5 Flash Preview (thinking) vs OpenAI o3

Compare Gemini 2.5 Flash Preview (thinking) by Google AI against OpenAI o3 by OpenAI, tested across 20 shared challenges. Updated April 2026.

Which is better, Gemini 2.5 Flash Preview (thinking) or OpenAI o3?

Gemini 2.5 Flash Preview (thinking) and OpenAI o3 are both competitive models. Gemini 2.5 Flash Preview (thinking) costs $0.175/M input tokens vs $10/M for OpenAI o3. Compare their real outputs side by side below.

Key Differences Between Gemini 2.5 Flash Preview (thinking) and OpenAI o3

Gemini 2.5 Flash Preview (thinking) is made by google while OpenAI o3 is from openai. On pricing, Gemini 2.5 Flash Preview (thinking) costs $0.175/M input tokens vs $10/M for OpenAI o3.

Our Verdict
OpenAI o3
OpenAI o3
Gemini 2.5 Flash Preview (thinking)
Gemini 2.5 Flash Preview (thinking)Runner-up

No community votes yet. On paper, OpenAI o3 has the edge — bigger model tier.

Gemini 2.5 Flash Preview (thinking) is 11x cheaper per token — worth considering if cost matters.

Too close to call
Writing DNA

Style Comparison

Similarity
100%

OpenAI o3 uses 37.9x more headings

Gemini 2.5 Flash Preview (thinking)
OpenAI o3
53%Vocabulary68%
14wSentence Length14w
0.38Hedging0.26
4.4Bold0.7
4.1Lists3.0
0.00Emoji0.00
0.00Headings0.38
0.24Transitions0.12
Based on 7 + 16 text responses
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Gemini 2.5 Flash Preview (thinking)OpenAI o3

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