Looking Back at GPT-5.1-Codex-Max—Official Facts vs. the Original Review

This is a historical page about a model available in December 2025. The old version's “3–10× faster,” “100 hours of development value,” fixed monthly price, and “128k–200k” claims were not supported by a recorded test or the cited official material, so this revision withdraws them.

What the launch establishes

On November 19, 2025, OpenAI announced GPT-5.1-Codex-Max as an agentic coding model for Codex. The announcement described compaction across multiple context windows, availability in Codex surfaces at launch, and the plans eligible at that time. OpenAI launch post

It did not guarantee that the model would understand every repository, fix every bug, or equal a senior engineer. A vendor benchmark and an individual project outcome are different forms of evidence.

What remains an historical impression

The owner's original article described long tasks as easier to sustain and debugging as easier to keep in one workflow. That is a dated, subjective assessment. Because the article did not record task definitions, baselines, or timing, it cannot support a productivity multiplier.

Do not use the old price as a current recommendation

Plans, usage limits, and credit options change. OpenAI's current help article says limits vary by plan and directs users to their usage page and current documentation. Using Codex with your ChatGPT plan

Before buying, check:

• local price and taxes;
• included Codex usage;
• what happens at a limit;
• whether the required model and feature are currently available.

A 15-minute comparison

Run the same small change once with the candidate model and once with your usual method:

1. Fix the acceptance criteria and tests.
2. Record time to passing tests.
3. Record human corrections and missed requirements.
4. Record usage and limit impact.
5. Repeat and compare medians, not the best run.

This measures value for your work without turning one demonstration into a universal multiplier.

Takeaway

GPT-5.1-Codex-Max was an important long-horizon Codex model at launch. The original article's fixed price and productivity promises were not verified. Use current official terms and your own repeated work log for a purchase decision.