OpenAI API pricing in 2026: GPT-4o, GPT-4o mini, o1 and real cost

The price of the OpenAI API remains a major benchmark for teams building AI products, assistants, writing workflows and support tools. But between GPT-4o, GPT-4o mini, reasoning models like o1 and the split between input and output cost, it is easy to miscalculate.

How OpenAI pricing works

OpenAI mainly charges for:

• tokens sent to the model;
• tokens generated by the model.

Your bill therefore depends on prompt length, output length, call volume and model choice.

GPT-4o vs GPT-4o mini vs o1

GPT-4o

Best for broad, high-quality and multimodal workloads.

GPT-4o mini

Best for lower-cost, high-volume tasks where premium quality is not always necessary.

o1

Best for more demanding reasoning-heavy use cases.

Common mistakes

• assuming ChatGPT Plus includes API access;
• using GPT-4o for every workflow;
• ignoring output-token cost.

Conclusion

OpenAI API pricing in 2026 is not just a rate-card question. It is an architecture question. The best approach is often to route simple tasks to cheaper models and keep premium models for high-value tasks.