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LLM Model Routing Explained: Pay Less Without Worse Answers

Routing sends each request to the cheapest model or provider that can handle it well. Done carefully, it's one of the biggest cost levers.

Two kinds of routing

• Provider routing: the same model, served by different authorized providers, chosen by price, latency and reliability. Quality doesn't change.
• Model routing: a different, cheaper model for requests that don't need the expensive one. Quality must be tested.

Common strategies

• Rules: route by task type, such as classification to a small model.
• Classifiers: a small model predicts difficulty and picks the model.
• Cascading: try a cheap model first, escalate if a check fails.
• Fallback: switch providers or models when one errors or slows down.

How to route without quality loss

1. Build an evaluation set from real requests.
2. Test the cheaper model offline.
3. Roll out to a small share of traffic and compare.
4. Keep a one-step rollback.

What it's worth

Price gaps between models are large: Claude Haiku 5.5 is a fortieth of Claude Opus 5.5's price per token, and GPT-6 Luna a twentieth of GPT-6.1 Sol's. Even moving a share of simple traffic adds up. Compare models in the LLM pricing comparison.

apicuts routes on cost per successful task, with your approval and your evals. See how routing works.

Frequently asked questions

Sources: Anthropic's pricing page, OpenAI's API pricing page. Checked October 30, 2026.

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