GPT 5.1 Codex
Chat
Deprecated
by OpenAI
This model has been deprecated by OpenAI and is no longer available for use. Please explore other available models below.
Overview
GPT-5.1 Codex is OpenAI's coding-optimized model built on the GPT-5.1 architecture with dynamic reasoning adjustment. Delivers strong software engineering performance with 2-3x faster speed and extended prompt caching.
Key Features
- Coding-optimized model built on GPT-5.1 with dynamic reasoning adjustment for development tasks.
- 400,000-token context window with 128,000 max output tokens and configurable reasoning effort.
- 2-3x faster than GPT-5 with ~50% token efficiency for cost-effective coding workflows.
- Extended prompt caching retention up to 24 hours with 90% cheaper cached input tokens.
- Pricing is $1.25 per 1M input tokens and $10 per 1M output tokens.
Input Capabilities
Text
Image
Document
Technical Specifications
Context Window
400,000
Max Output
128,000
Streaming
Supported
Model Information
Provider: OpenAI
Model Code: gpt-5.1-codex
Category: Chat
File Support
Max Files
20
Max Size
50MB
Supported Formats
.png
.jpg
.jpeg
.webp
.gif
.pdf
+24 more
Other OpenAI Models
GPT 5.6 SolGPT-5.6 Sol is OpenAI's flagship model in the GPT-5.6 family, released July 9, 2026, for the most complex professional work spanning software engineering, long-horizon research, agentic tool use, and careful result refinement.
GPT 5.6 TerraGPT-5.6 Terra balances capability and cost efficiency for everyday production workloads in the GPT-5.6 family, released July 9, 2026.
GPT 5.6 LunaGPT-5.6 Luna is the fastest, most cost-optimized model in the GPT-5.6 family, released July 9, 2026, built for high-volume and latency-sensitive workloads.