
Fine-Tuning vs RAG vs Prompting: How to Customize an LLM in 2026 (Cost, Effort, and a Decision Flowchart)
Fine-tuning, RAG, and prompting are the three ways to customize an LLM. Here is a decision flowchart, real cost math, and the one rule that prevents the most expensive mistake: prompt first, retrieve for knowledge, fine-tune for behavior.









