How to Track LLM Costs Across Providers with LiteLLM

When several apps and teammates hit different LLM providers, the bill becomes guesswork. LiteLLM solves that by routing everything through one proxy that meters spend per key. You get a single place to see who spent what, and you can cap it before the invoice surprises you.

This builds on the basic LiteLLM proxy setup. Start there if you have not run litellm --config config.yaml yet — here we focus on the accounting layer.

How do LiteLLM virtual keys work?

A virtual key is a scoped token you hand to an app or a person. It maps to one or more models, carries its own spend limit, and can expire. Requests made with that key are attributed to it, so usage reports break down by key rather than by a shared provider account.

How do you set a budget?

1. Enable the database so LiteLLM can persist spend (Postgres).
2. Create a key with max_budget — say $50 per month.
3. Optionally set budget_duration: 30d so the cap resets monthly.
4. Set a rpm_limit and tpm_limit to stop runaway loops.
5. Hand the key to the app; let LiteLLM enforce the ceiling.

When a key hits its limit, requests fail until the window resets — a hard stop that protects the wallet.

How do you attribute spend to teams or projects?

Use tags and teams. Tag a group of keys by project, or create a team with a shared budget and issue child keys. Reports then roll up by tag or team, which is what finance asks for. Without tagging, you get totals but no ownership.

Which logging destinations are supported?

LiteLLM can export usage to Langfuse, Helicone, Prometheus, or a plain database, and it exposes an admin UI that shows recent spend. Pick one destination and stick to it rather than duplicating logs in several tools.

What are the real limits?

The cost estimates depend on per-model pricing tables; a brand-new model may be priced wrong until LiteLLM updates its list. Self-hosting means you also run Postgres and keep it backed up. And a budget stops spend, not bad prompts — it will not tell you that a loop is burning tokens for no output, only that the key is out of money.

Key Takeaways

• Virtual keys attribute LLM spend to a specific app or person.
• Set max_budget and budget_duration to cap monthly spend.
• Use tags or teams to roll costs up by project.
• Logs export to Langfuse, Helicone or Prometheus.
• Budget enforcement needs the Postgres database enabled.

Last updated October 2026. More on the LiteLLM page.