GPT-5.1 Codex Max
Pricing & Specs
OpenAI · $1.25 input / $10 output per 1M tokens · 400K context window
No longer offered on OpenMark
GPT-5.1 Codex Max is no longer offered on OpenMark (deprecated or superseded upstream). Its specs are kept here for reference. If you're still running it in production, it's worth benchmarking current alternatives: newer models are often cheaper AND better on the same task.
GPT-5.1 Codex Max API Pricing
| Tokens | Price |
|---|---|
| Input | $1.25 / 1M tokens |
| Output | $10 / 1M tokens |
| Cached input | $0.125 / 1M tokens |
Cached input tokens are billed when caching is enabled.
What that means in practice
GPT-5.1 Codex Max Specs
| Spec | Value |
|---|---|
| Context window | 400K tokens |
| Max input per request | 272K tokens |
| Max output tokens | 128K tokens |
| Input modalities | text, image |
| Output modalities | text |
| Latency (measured by OpenMark) | ~1.2s median response |
| Reasoning model | Yes |
| Tool / function calling | Yes |
| JSON mode | Yes |
| Streaming | Yes |
| Prompt caching | Yes |
| Batch API | No |
Notes
Shut down July 23, 2026. Shutdown July 23, 2026.
FAQ
How much does GPT-5.1 Codex Max cost?
GPT-5.1 Codex Max costs $1.25 per 1M input tokens and $10 per 1M output tokens ($0.125 per 1M cached input tokens).
What is GPT-5.1 Codex Max's context window?
GPT-5.1 Codex Max has a 400K-token context window. Maximum output is 128K tokens.
Can I test GPT-5.1 Codex Max on my own task?
GPT-5.1 Codex Max is no longer offered on OpenMark, but you can benchmark its current alternatives from OpenAI and other providers on your own task, free tier available.
Still using GPT-5.1 Codex Max?
It's been superseded. Benchmark its current alternatives on your actual
workload. You'll likely find something cheaper AND better. Free tier available.