Compare · Building
Prompting vs RAG vs fine-tuning
Three levers, three jobs. Use this order so you do not fine-tune your way out of a prompting problem — or retrieve your way out of a style problem.
Decision table
- Prompting — best first move for structure, tone sketches, and few-shot examples you can inspect.
- RAG — best when facts live in docs that change and must be cited.
- Fine-tuning — best when behavior/format must stick across many similar tasks after prompting plateaus.
- Cost curve — prompts are cheapest to iterate; RAG adds infra; fine-tunes add training + ongoing evals.
Recommended order
1) Write a prompt contract. 2) If knowledge is private or changing, add RAG. 3) If format still drifts, consider LoRA / fine-tuning. Compare two techniques in depth on RAG vs fine-tuning.
FAQ
What should I try first?
Start with a clear prompt contract and examples. Add RAG when answers must cite changing documents. Fine-tune only when style or format still drifts after good prompts and retrieval.
Can I use all three?
Yes. Many production systems prompt carefully, retrieve for facts, and fine-tune for format or tone. Evaluate each layer separately.