Claude Sonnet 4.5 vs Google: Gemini 2.5 Flash Preview 09-2025
Compare Claude Sonnet 4.5 by Anthropic against Google: Gemini 2.5 Flash Preview 09-2025 by Google AI, context windows of 200K vs 1.0M, tested across 43 shared challenges.
Our Verdict
Google: Gemini 2.5 Flash Preview 09-2025
Claude Sonnet 4.5Runner-up
No community votes yet. On paper, Google: Gemini 2.5 Flash Preview 09-2025 has the edge — bigger model tier, bigger context window.
Google: Gemini 2.5 Flash Preview 09-2025 is 6.0x cheaper per token — worth considering if cost matters.
Too close to call
API pricing
Cost per 1M tokens
Claude Sonnet 4.5
Input
$3.00
Output
$15.00
Google: Gemini 2.5 Flash Preview 09-2025
Input
$0.30
10× cheaper
Output
$2.50
6.0× cheaper
Google: Gemini 2.5 Flash Preview 09-2025 is cheaper on both — 10× input, 6.0× output
Writing DNA
Style Comparison
Similarity
43%
Claude Sonnet 4.5 uses 5.0x more sentence length
Claude Sonnet 4.5
Google: Gemini 2.5 Flash Preview 09-2025
64%Vocabulary53%
94wSentence Length19w
0.48Hedging0.30
4.9Bold5.8
8.0Lists3.1
0.45Emoji0.14
1.91Headings0.93
0.07Transitions0.22
Based on 20 + 22 text responses
Research
What we learned reading every model
FAQ
