GPT-4.1vsGPT-5.1 Codex Max
GPT-5.1 Codex Max is the newer model, released after GPT-4.1.
| Spec | GPT-4.1 | GPT-5.1 Codex Max |
|---|---|---|
| Input price | $2/M tokens | — |
| Output price | $8/M tokens | — |
| Context window | 1.0M tokens | — |
| Weights | Closed | Closed |
| Free API (OpenRouter) | No | No |
| Released | Apr 2025 | Dec 2025 |
| SWE-bench Verified | 54.6% | 77.9% |
Our Verdict
GPT-4.1
GPT-5.1 Codex Max
Not enough votes to call it. On the specs, nothing separates them.
Too close to call
API pricing
Cost per 1M tokens
GPT-4.1
Input
$2.00
Output
$8.00
GPT-5.1 Codex Max
Input
—
Output
—
Where to run it
3 hosts
GPT-5.1 Codex Max1 host
Per million tokens. Prices and uptime via OpenRouter, checked 9 Sep 2026.
Writing DNA
Style Comparison
Similarity
41%
GPT-4.1 uses 21.9x more emoji
GPT-4.1
GPT-5.1 Codex Max
58%Vocabulary60%
19wSentence Length16w
0.49Hedging0.36
8.8Bold2.3
5.8Lists4.2
0.22Emoji0.00
1.01Headings0.12
0.10Transitions0.03
Based on 27 + 13 text responses
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