OpenAI has introduced Reinforcement Fine-Tuning (RFT) for its o4-mini reasoning model, a powerful technique that leverages reinforcement learning principles to tailor foundation models for specialized tasks. This method allows developers to define custom objectives and reward functions, enabling fine-grained control over model behavior beyond traditional supervised fine-tuning.
RFT applies reinforcement learning to language model fine-tuning. Instead of relying solely on labeled examples, developers provide a task-specific grader—a function that evaluates and scores model outputs based on custom criteria. The model is trained to optimize against this reward signal, gradually learning to generate responses that align with desired behavior. This approach is particularly useful for nuanced or subjective tasks where ground truth is difficult to define.
OpenAI’s o4-mini is a compact reasoning model optimized for both text and image inputs. It excels in structured reasoning and chain-of-thought prompts, making it ideal for high-stakes, domain-specific tasks. RFT on o4-mini allows developers to precisely tune the model while maintaining computational efficiency and real-time performance.
RFT has been successfully applied in various domains, including:
RFT is available to verified organizations. Training costs are billed at $100/hour, with a 50% discount for organizations that share their datasets for research purposes. Token usage for grader calls (e.g., GPT-4o) is charged separately at standard inference rates.
Reinforcement Fine-Tuning on o4-mini represents a significant advancement in model customization, enabling developers to fine-tune not just language but reasoning itself. By leveraging RFT, organizations can create highly specialized AI solutions that align with their unique requirements.
For more details, refer to OpenAI’s RFT documentation.