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GPT-5.1 Codex
A version of GPT-5.1 optimized for agentic coding in Codex.
| Context window | 200,000 tokens |
| Max output tokens | 4,096 tokens |
Pricing
| Type | Input | Output |
|---|---|---|
| Standard | $2.50 / 1M tokens | $20.00 / 1M tokens |
| Cached input | $0.25 / 1M tokens | |
Parameters
| Parameter | Default | Range |
|---|---|---|
| Max stop sequences | 0 | — |
Supported features
Capabilities
- Streaming
- Reasoning
- System Prompt
Endpoints
- Chat Completions
- Batch
Tools
- Code Interpreter
Use cases
- text-chat
Model specifications
| Model ID | gpt-5.1-codex |
| Family | Other |
| Access type | Closed |
| Input modalities | text |
| Output modalities | text |
| Last updated | January 3, 2026 |