GPT-5.1 Codex
Parameters
-
Context Length
400K
Modality
Text
Architecture
Dense
License
Proprietary
Release Date
13 Nov 2025
Knowledge Cutoff
-
Technical Specifications
Attention Structure
Multi-Head Attention
Hidden Dimension Size
-
Number of Layers
-
Attention Heads
-
Key-Value Heads
-
Activation Function
-
Normalization
-
Position Embedding
Absolute Position Embedding
GPT-5.1 Codex
Specialized coding model in GPT-5.1 series with excellent programming capabilities. Strong performance in coding benchmarks (81.98 reasoning for code, 71.78 coding, 68.80 general coding). Effective at web development (Elo 1335) and software engineering tasks. Optimized for code generation, debugging, and technical problem-solving.
About GPT-5
OpenAI's latest generation of language models featuring advanced reasoning capabilities, extended context windows up to 400K tokens, and specialized variants for coding, general intelligence, and efficiency. GPT-5 series introduces improved thinking modes, superior performance across benchmarks, and variants optimized for different use cases from high-capacity Pro models to efficient Nano models. Features native multimodal understanding, enhanced mathematical reasoning, and state-of-the-art coding abilities through Codex variants.
Other GPT-5 Models
Evaluation Benchmarks
Rank
#15
| Benchmark | Score | Rank |
|---|---|---|
Reasoning LiveBench Reasoning | 0.82 | ⭐ 4 |
Agentic Coding LiveBench Agentic | 0.64 | ⭐ 7 |
Mathematics LiveBench Mathematics | 0.70 | 23 |
Web Development WebDev Arena | 1335 | 26 |
Coding LiveBench Coding | 0.72 | 27 |
Rankings
Overall Rank
#15
Coding Rank
#35