How Much Does an AI Agent Cost?

Question

How much does an AI agent cost?

Quick answer

Formula: cost_per_user_month = generation + retrieval + reranking + embeddings_ingestion + vector_db + cache + infra

• Assumption: this structure fits retrieval-heavy AI agents, copilots, and support assistants especially well.
• Assumption: cache is modeled as a signed savings term and can be negative.
• Assumption: monthly cost should be paired with explicit requests-per-user assumptions, not one vague average.

Example: if generation=$1.80, retrieval=$0.60, reranking=$0.30, embeddings_ingestion=$0.20, vector_db=$0.10, cache=-$0.40, and infra=$0.20, cost_per_user_month=$2.80.

Fastest Working Method

1. Estimate requests per active user and tokens per workflow.
2. Break the workflow into generation, retrieval, reranking, cache, vector, and infra terms.
3. Roll the result up to cost per user/month before discussing price or packaging.
4. Check which component dominates before adding more complexity.

What Usually Moves Cost Most

• Request frequency per user.
• Retrieved context size and rerank depth.
• Model choice for generation and fallback traffic.
• Cache hit rate and repeated-answer reuse.
• How often the knowledge base is re-embedded.

When a Simple Estimate Breaks

• If the workflow loops multiple times before answering.
• If tool calls or API actions are a material share of spend.
• If p90 sessions are much larger than average sessions.