OpenAI Codex CLI Pricing Guide 2026

Codex CLI is OpenAI's command-line tool for AI-assisted coding. It uses OpenAI's o-series models and GPT-4o under the hood. Like other CLI tools, the software is free — you pay for API usage.

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OpenAI Codex CLI Pricing Plans

ComponentCostDetails
Codex CLIFreeOpen source CLI from OpenAI
o3 model$10.00/M input, $40.00/M outputLatest reasoning model
o3-mini$1.10/M input, $4.40/M outputBudget reasoning
gpt-4o$2.50/M input, $10.00/M outputGeneral purpose

Best AI Models for OpenAI Codex CLI (2026)

Based on cost-effectiveness, coding quality, and availability. Data updated Apr 18, 2026.

💰 Cheapest

GPT-4o mini

OpenAI · $0.150/M input

High-volume tasks, simple coding, cost-sensitive projects

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⚡ Best Value

GPT-4o mini

OpenAI · $0.150/M input

High-volume tasks, simple coding, cost-sensitive projects

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🏆 Premium

GPT-4

OpenAI · $30.00/M input

Legacy applications requiring GPT-4 specifically

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Cost Per Session with OpenAI Codex CLI

Estimated cost for a medium feature implementation (100K input + 10K output tokens).

ModelProviderCost/SessionInput PriceOutput Price
GPT-4o mini OpenAI $0.18 $0.150/M $0.600/M
GPT-4.1 mini OpenAI $0.46 $0.400/M $1.60/M
GPT-3.5 Turbo OpenAI $0.48 $0.500/M $1.50/M
OpenAI o1-mini OpenAI $1.27 $1.10/M $4.40/M
OpenAI o3-mini OpenAI $1.27 $1.10/M $4.40/M
OpenAI o4-mini OpenAI $1.27 $1.10/M $4.40/M

Frequently Asked Questions

Is Codex CLI free?

The CLI is free and open source. You pay for OpenAI API usage.

What models does Codex CLI use?

Codex CLI uses OpenAI's o3, o3-mini, and GPT-4o models depending on the task complexity.

How much does a typical Codex CLI session cost?

With o3-mini, a medium feature costs about $0.15. With GPT-4o, about $0.35.

Compare OpenAI Codex CLI with Other Platforms

See how OpenAI Codex CLI stacks up against the competition.

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