Gemini 1.5 Pro vs Gemini 2.5 Flash Preview 05-20
Compare Gemini 1.5 Pro and Gemini 2.5 Flash Preview 05-20, both from Google AI, context windows of 1.0M vs 1.0M, tested across 1 shared challenge. Updated April 2026.
Which is better, Gemini 1.5 Pro or Gemini 2.5 Flash Preview 05-20?
Gemini 1.5 Pro and Gemini 2.5 Flash Preview 05-20 are both competitive models. Gemini 1.5 Pro costs $3.5/M input tokens vs $0.15/M for Gemini 2.5 Flash Preview 05-20. Context windows: 1000K vs 1049K tokens. Compare their real outputs side by side below.
Key Differences Between Gemini 1.5 Pro and Gemini 2.5 Flash Preview 05-20
Gemini 1.5 Pro is made by google while Gemini 2.5 Flash Preview 05-20 is from google. Gemini 1.5 Pro has a 1000K token context window compared to Gemini 2.5 Flash Preview 05-20's 1049K. On pricing, Gemini 1.5 Pro costs $3.5/M input tokens vs $0.15/M for Gemini 2.5 Flash Preview 05-20.
Our Verdict
Gemini 1.5 Pro
Gemini 2.5 Flash Preview 05-20
No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.
Gemini 2.5 Flash Preview 05-20 is 18x cheaper per token — worth considering if cost matters.
Too close to call
Writing DNA
Style Comparison
Similarity
98%
Gemini 1.5 Pro uses 8.1x more headings
Gemini 1.5 Pro
Gemini 2.5 Flash Preview 05-20
61%Vocabulary69%
15wSentence Length10w
0.80Hedging0.26
3.7Bold1.1
3.3Lists5.5
0.00Emoji0.00
0.08Headings0.00
0.09Transitions0.00
Based on 8 + 2 text responses
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279 AI models invented the same fake scientist.
We read every word. 250 models. 2.14 million words. This is what we found.
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