RAG vs Fine-Tuning: Which One Do You Actually Need?

One of the most common questions I get: should I use RAG or fine-tune my model? The answer, as always, is “it depends” — but the decision is simpler than it looks.

Use RAG when…

Your knowledge changes often, you need citations, or you want to ground answers in private data without retraining.

Fine-tune when…

You need a specific style, format, or behaviour that prompting alone cannot reliably produce.

Often, you need both

The most robust systems combine retrieval for knowledge with light fine-tuning for behaviour.