Gemini 3.1 Pro PreviewvsGPT-5 Codex
Gemini 3.1 Pro Preview is the newer model, released after GPT-5 Codex.
| Spec | Gemini 3.1 Pro Preview | GPT-5 Codex |
|---|---|---|
| Input price | $2/M tokens | — |
| Output price | $12/M tokens | — |
| Context window | 1.0M tokens | — |
| Weights | Closed | — |
| Free API (OpenRouter) | No | No |
| Released | Feb 2026 | Sep 2025 |
| SWE-bench Verified | 80.6% | 74.5% |
Our Verdict
Gemini 3.1 Pro Preview
GPT-5 Codex
Not enough votes to call it. On the specs, nothing separates them.
Too close to call
Reviewing agent-written code?See a Brief PR report
API pricing
Cost per 1M tokens
Gemini 3.1 Pro Preview
Input
$2.00
Output
$12.00
GPT-5 Codex
Input
—
Output
—
Where to run it
2 hosts, cheapest first
Gemini 3.1 Pro Preview2 hosts
GPT-5 Codex
No hosts listed on OpenRouter.
Per million tokens. Prices and uptime via OpenRouter, checked 12 Sep 2026.
Writing DNA
Style Comparison
Similarity
50%
GPT-5 Codex uses 14.6x more emoji
Gemini 3.1 Pro Preview
GPT-5 Codex
54%Vocabulary64%
18wSentence Length17w
0.29Hedging0.38
4.9Bold2.3
3.3Lists3.5
0.00Emoji0.15
0.72Headings0.49
0.14Transitions0.05
Based on 23 + 13 text responses
Research
What we learned reading every model
FAQ
Common questions
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