Gemini 2.5 Flash Preview (thinking) vs Claude Opus 4

Compare Gemini 2.5 Flash Preview (thinking) by Google AI against Claude Opus 4 by Anthropic, in 1 community votes, gemini 2.5 flash preview (thinking) wins 100% of head-to-head duels, context windows of 1.0M vs 200K, tested across 14 shared challenges. Updated April 2026.

Which is better, Gemini 2.5 Flash Preview (thinking) or Claude Opus 4?

Gemini 2.5 Flash Preview (thinking) is the better choice overall, winning 100% of 1 blind community votes on Rival. Gemini 2.5 Flash Preview (thinking) costs $0.175/M input tokens vs $15/M for Claude Opus 4. Context windows: 1049K vs 200K tokens. Compare their real outputs side by side below.

Key Differences Between Gemini 2.5 Flash Preview (thinking) and Claude Opus 4

Gemini 2.5 Flash Preview (thinking) is made by google while Claude Opus 4 is from anthropic. Gemini 2.5 Flash Preview (thinking) has a 1049K token context window compared to Claude Opus 4's 200K. On pricing, Gemini 2.5 Flash Preview (thinking) costs $0.175/M input tokens vs $15/M for Claude Opus 4. In community voting, In 1 community votes, Gemini 2.5 Flash Preview (thinking) wins 100% of head-to-head duels.

In 1 community votes, Gemini 2.5 Flash Preview (thinking) wins 100% of head-to-head duels. Based on blind community voting from the Rival open dataset of 1+ human preference judgments for this pair.

Our Verdict
Gemini 2.5 Flash Preview (thinking)
Gemini 2.5 Flash Preview (thinking)Winner
Claude Opus 4
Claude Opus 4Runner-up

Pick Gemini 2.5 Flash Preview (thinking). In 1 blind votes, Gemini 2.5 Flash Preview (thinking) wins 100% of the time. That's not luck.

Gemini 2.5 Flash Preview (thinking) is 21x cheaper per token — worth considering if cost matters.

Clear winner
Writing DNA

Style Comparison

Similarity
94%

Claude Opus 4 uses 11.2x more emoji

Gemini 2.5 Flash Preview (thinking)
Claude Opus 4
53%Vocabulary64%
14wSentence Length62w
0.38Hedging0.52
4.4Bold4.4
4.1Lists9.1
0.00Emoji0.11
0.00Headings1.87
0.24Transitions0.27
Based on 7 + 16 text responses
vs

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Gemini 2.5 Flash Preview (thinking)Claude Opus 4

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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