Gemini 3.5 Flash vs GPT-5.1-Codex
Compare Gemini 3.5 Flash by Google AI against GPT-5.1-Codex by OpenAI, context windows of 1.0M vs 400K, tested across 52 shared challenges.
Our Verdict
Gemini 3.5 Flash
GPT-5.1-Codex
No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.
Too close to call
API pricing
Cost per 1M tokens
Gemini 3.5 Flash
Input
$1.50
Output
$9.00
1.1× cheaper
GPT-5.1-Codex
Input
$1.25
1.2× cheaper
Output
$10.00
GPT-5.1-Codex wins input (1.2× cheaper)·Gemini 3.5 Flash wins output (1.1× cheaper)
Writing DNA
Style Comparison
Similarity
51%
GPT-5.1-Codex uses 3.6x more transitions
Gemini 3.5 Flash
GPT-5.1-Codex
59%Vocabulary70%
18wSentence Length17w
0.16Hedging0.39
4.4Bold3.4
3.0Lists3.5
0.00Emoji0.00
0.89Headings0.50
0.11Transitions0.38
Based on 27 + 14 text responses
Research
What we learned reading every model
FAQ
