---
title: How much does it cost to build a RAG system?
source: https://rubradigital.com/answers/how-much-does-a-rag-system-cost
site: Rubra Digital
description: Real cost ranges for building and running a production RAG system in 2026: build cost, monthly running cost, and what moves the number most.
updated: 2026-07-14
topic: cost
also_asked: What does a RAG project cost? | How much does enterprise RAG cost per month? | Is RAG expensive to run?
---

# How much does it cost to build a RAG system?

**Summary:** A production RAG system typically costs between €60,000 and €180,000 to build with an external partner, or roughly three to six months of a two-person internal team. Running costs are much lower than most teams expect: €500 to €4,000 per month for a typical internal deployment serving a few thousand queries a day, covering inference, embeddings, vector storage and hosting. The build cost is driven far more by document complexity and the number of source systems than by query volume. Scanned PDFs and table-heavy documents can double the engineering effort.

## Build cost: what the range actually depends on

The two things that move build cost most are not the ones teams expect.

**Document complexity.** A corpus of clean, digital, text-first documents is a
straightforward ingestion job. A corpus of scanned PDFs, engineering drawings,
documents where the meaning lives in tables, or files exported from a system
that lost the structure can double or triple the parsing effort. This is the
single most common source of budget overrun, and it is knowable in week one if
anyone looks.

**Number of source systems.** One SharePoint library is one integration. Six
systems with different auth models, permission schemes and update cadences is a
different project, and permission-aware retrieval across all of them is harder
still.

Rough bands, for delivery with an experienced partner:

| Scope                                                | Typical range      |
| ---------------------------------------------------- | ------------------ |
| Prototype on a clean single corpus                   | €15,000 – €30,000  |
| Production system, one corpus, internal users        | €60,000 – €95,000  |
| Production system, several sources, permission-aware | €95,000 – €180,000 |
| Customer-facing, regulated, multilingual             | €180,000+          |

An internal build is not free: the same work is roughly three to six months of
two capable engineers, plus the learning curve if this is their first such
system.

## Running cost: usually the smaller number

For a system handling around 3,000 queries a day over a corpus of a few hundred
thousand chunks, a representative monthly bill in 2026:

- **Generation.** €300 to €2,500, depending heavily on model choice and how much
  context is stuffed into each prompt
- **Embeddings.** €20 to €150. Re-embedding on document change is minor
- **Vector storage.** €0 if you use pgvector on a database you already run, up
  to €700 for a managed vector service at this scale
- **Reranking.** €50 to €400
- **Hosting and observability.** €100 to €500

Teams routinely over-provision here. The most common waste is sending 8,000
tokens of context when 2,000 would answer the question equally well, and routing
every request to the largest available model regardless of difficulty.

## What reduces cost without hurting quality

- **Caching.** Exact-match plus semantic caching typically removes 25–45% of
  calls in assistant-style workloads.
- **Right-sizing the model per request.** Route simple lookups to a small model,
  hard synthesis to a large one. Verify with evaluation, because this quietly
  degrades some task types.
- **Tighter retrieval.** Better reranking means fewer passages needed, which
  means shorter prompts and lower cost per call.
- **Prompt-prefix caching** where the provider supports it, for the static
  instruction block.

## The cost nobody budgets

Evaluation. Building the labelled set and the harness is typically 15–25% of the
project, and it is the line most often cut. It is also the line that determines
whether you can safely change anything after launch. Cutting it does not save
money, it defers a larger cost to month six.

---

Source: https://rubradigital.com/answers/how-much-does-a-rag-system-cost
Rubra Digital. Independent LLM and RAG consulting for regulated and document-heavy organisations in Europe and North America.
Contact: hello@rubradigital.com