OpenAI: GPT-5.1-Codex API Price, Cost Calculator & Specs

At $10/1M output tokens, Codex will devastate your margins on any $20/month subscription unless you're handling enterprise-level coding. But here's the thing—it's actually worth it for the right tasks. The specialization shows up in how it handles complex refactoring, catching subtle bugs that cheaper models miss, and maintaining code consistency across large codebases.

The price gap with GPT-5.1-Codex-Mini ($0.25/$2 input/output) makes this a tactical choice. Use Codex for what it does uniquely well: multi-file architecture planning, production debugging, and code review at enterprise scale. For routine CRUD operations, basic API endpoints, and simple CRUD interfaces? Send those to the mini version.

Where Codex Shines:

Production Code Reviews: It catches dependency issues and security patterns that generic models miss. Worth the cost when you're reviewing critical code paths where a single bug could cost thousands in downtime.

Enterprise Refactoring: Handles large-scale code transformations while maintaining architectural consistency. Traditional models tend to break interfaces or introduce subtle regressions.

Complex Debugging: Follows call stacks across multiple services and understands the business logic context. Cheaper models often get lost in complex systems.

Agentic Workflows: Acts as the strategic planner, breaking down complex features into implementable chunks while delegating implementation to smaller, faster models.