GPT-5 NanovsGPT-5.1
GPT-5.1 is the newer model, released after GPT-5 Nano.
| Spec | GPT-5 Nano | GPT-5.1 |
|---|---|---|
| Input price | — | $1.25/M tokens |
| Output price | — | $10/M tokens |
| Context window | — | 400K tokens |
| Weights | Closed | Closed |
| Free API (OpenRouter) | No | No |
| Released | Aug 2025 | Nov 2025 |
| SWE-bench Verified | 54.7% | 76.3% |
Our Verdict
GPT-5.1
GPT-5 NanoRunner-up
Not enough votes to call it. On the specs, GPT-5.1 has the edge: bigger model tier, newer, bigger context window.
Too close to call
API pricing
Cost per 1M tokens
GPT-5 Nano
Input
—
Output
—
GPT-5.1
Input
$1.25
Output
$10.00
Where to run it
4 hosts
Per million tokens. Prices and uptime via OpenRouter, checked 8 Sep 2026.
Writing DNA
Style Comparison
Similarity
61%
GPT-5.1 uses 349.6x more bold
GPT-5 Nano
GPT-5.1
60%Vocabulary62%
25wSentence Length19w
0.26Hedging0.29
0.0Bold3.5
4.4Lists7.2
0.00Emoji0.00
0.00Headings0.61
0.03Transitions0.03
Based on 20 + 14 text responses
Research
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FAQ
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