{"id":47,"date":"2026-03-22T10:45:00","date_gmt":"2026-03-22T10:45:00","guid":{"rendered":"https:\/\/numriq.com\/rag-fine-tuning-prompt-engineering-en\/"},"modified":"2026-03-22T10:45:00","modified_gmt":"2026-03-22T10:45:00","slug":"rag-fine-tuning-prompt-engineering-en","status":"publish","type":"post","link":"https:\/\/numriq.com\/en\/rag-fine-tuning-prompt-engineering-en\/","title":{"rendered":"RAG, fine-tuning, prompt engineering: choosing the right approach"},"content":{"rendered":"<p>&#8220;We&#8217;re going to fine-tune a model.&#8221; Seven times out of ten, it&#8217;s not the right solution. Here&#8217;s how to differentiate the three main approaches to customize AI to your context.<\/p>\n<h2>Prompt engineering<\/h2>\n<p>You write carefully structured instructions, you provide examples in the prompt, you iterate. No changes to the model, just better input. It&#8217;s the cheapest approach, fastest to deploy, and easiest to modify.<\/p>\n<p>When to use: for 80% of SMB use cases. If the task can be explained to a human in one page, it can probably be explained to an LLM by prompt.<\/p>\n<h2>RAG (Retrieval-Augmented Generation)<\/h2>\n<p>You index your knowledge base (internal documents, FAQs, manuals, database). At query time, you retrieve relevant passages and inject them into the prompt. The model responds with your up-to-date information.<\/p>\n<p>When to use: when your use case depends on information that changes (internal policies, product catalog, technical documentation), or that&#8217;s too large to fit in a prompt. It&#8217;s the standard approach for internal help chatbots, customer support tools, and document research assistants.<\/p>\n<h2>Fine-tuning<\/h2>\n<p>You take a base model and train it on your own examples (typically high-quality question\/answer pairs). The model &#8220;learns&#8221; your style, your business vocabulary, or specific behavior hard to obtain otherwise.<\/p>\n<p>When to use: when you need a very specific style (brand tone, strict output format), rare business vocabulary, or a precise classification task on a narrow domain. And when you have the data: minimum 500-1,000 quality examples, ideally more.<\/p>\n<h2>Quick decision framework<\/h2>\n<p>1. Does it work with a good prompt and examples? If yes, stop there.<\/p>\n<p>2. If not, can the missing information be indexed and retrieved on demand? If yes, RAG.<\/p>\n<p>3. If not, do you have 500+ examples of the ideal output? If yes, fine-tuning may be justified. If not, go back to 1.<\/p>\n<h2>Winning combinations<\/h2>\n<p>RAG + good prompt engineering is 90% of enterprise AI solutions. Fine-tuning + RAG, for cases where you want a very specific tone on a changing knowledge base. Fine-tuning alone, almost never except for very narrow classification cases.<\/p>\n<p>The trap: starting with &#8220;we&#8217;re going to fine-tune&#8221; before exhausting the first two options. Fine-tuning costs more, takes longer, and complicates maintenance. It&#8217;s a precision tool, not a starting point.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Three approaches, often confused, sometimes combined. A decision framework for knowing which to use for your case \u2014 cost, complexity, output quality.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[3],"tags":[],"class_list":["post-47","post","type-post","status-publish","format-standard","hentry","category-outils"],"acf":[],"_links":{"self":[{"href":"https:\/\/numriq.com\/en\/wp-json\/wp\/v2\/posts\/47","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/numriq.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/numriq.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/numriq.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/numriq.com\/en\/wp-json\/wp\/v2\/comments?post=47"}],"version-history":[{"count":0,"href":"https:\/\/numriq.com\/en\/wp-json\/wp\/v2\/posts\/47\/revisions"}],"wp:attachment":[{"href":"https:\/\/numriq.com\/en\/wp-json\/wp\/v2\/media?parent=47"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/numriq.com\/en\/wp-json\/wp\/v2\/categories?post=47"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/numriq.com\/en\/wp-json\/wp\/v2\/tags?post=47"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}