OpenAI · Released Nov 13, 2025GPT-5.1 Codex
Codex GPT for repository edits, code review, and practical software agents.
- Capability
- —No ECI score yet
- Input
- $1.25per 1M tokens
- Output
- $10.00per 1M tokens
- Context
- 400K128K max output
What it costs
- Input
- $1.25per million tokens
- Output
- $10.00per million tokens
- Blended (3:1)
- $3.44pricier than 78% of priced models
Typical monthly bills
| Monthly usage | Estimated cost |
|---|---|
| Side project2M input + 0.5M output tokens | $7.50 |
| Team assistant25M input + 5M output tokens | $81.25 |
| Production app250M input + 50M output tokens | $812.50 |
Median of 10 paid API providers on models.dev.
Independent benchmarks
Epoch AI has not published a Capabilities Index score for GPT-5.1 Codex yet.
The details
- Lab
- OpenAI
- Released
- Nov 13, 2025
- Knowledge cutoff
- Sep 30, 2024
- Context window
- 400,000 tokens
- Max output
- 128,000 tokens
- Inputs
- Text, Images
- Output
- Text
- Reasoning
- Always on
- Tool calling
- Yes
- Structured output
- Yes
- Weights
- Proprietary
- Availability
- 10 API providerslisted on models.dev
More from OpenAI
About GPT-5.1 Codex
How much does GPT-5.1 Codex cost?
GPT-5.1 Codex costs $1.25 input / $10.00 output per million tokens (median across 10 API providers). At a 3:1 input-to-output mix that is $3.44 per million tokens, more expensive than 78% of the 360 priced models we track.
What is the context window of GPT-5.1 Codex?
GPT-5.1 Codex accepts up to 400,000 tokens per request and can write up to 128,000 tokens in one response.
How good is GPT-5.1 Codex?
Epoch AI has not published a Capabilities Index score for GPT-5.1 Codex yet.
Is GPT-5.1 Codex open source?
No. GPT-5.1 Codex is proprietary; you use it through an API or partner platforms.
What inputs does GPT-5.1 Codex support?
GPT-5.1 Codex accepts text and images and replies in text. It is a reasoning model, supports tool calling and can return structured JSON output.
When was GPT-5.1 Codex released?
OpenAI released GPT-5.1 Codex on Nov 13, 2025. Its training data runs to Sep 30, 2024.
What are the best alternatives to GPT-5.1 Codex?
The closest current models from other labs on capability, price and release date are Gemini 2.5 Computer Use Preview (Google, $1.25 / $10.00), Jamba Large (AI21 Labs, $2.00 / $8.00), Command A Translate (Cohere, $2.50 / $10.00) and Kimi K2.7 Code Highspeed (Moonshot AI, $1.90 / $8.00).