> ## Documentation Index
> Fetch the complete documentation index at: https://docs.composo.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Credits

Credits are how Composo bills your usage. Your monthly contract maps to a credit allowance, and each evaluation call costs a fraction of a credit based on the input tokens it processed and which model it used.

## What a credit is

A credit is a fixed amount of evaluation compute. Each model has its own tokens-per-credit rate:

| Model                                                  | Tokens per credit |
| ------------------------------------------------------ | ----------------- |
| `align-20260109` / `align-20251111` / `align-20250529` | 1,000,000         |
| `align-lightning-20251127`                             | 1,000,000         |
| `align-lightning-20250731`                             | 2,000,000         |

Some Lightning variants stretch further per credit than Align — same workload, fewer credits — because they're cheaper for us to serve. If you're cost-sensitive, leaning on those models for high-volume use cases is the main lever.

Not sure which model you're calling? Check the `model_core` field in your API requests, or look at the per-model table on your `/usage` page.

<Note>
  Evaluating the **same trace under multiple criteria**? The reused trace tokens bill at a reduced rate — see [Trace caching](/documentation/billing/caching).
</Note>

## Why credits, not tokens

Tokens cost different amounts depending on the model. Credits normalise for that — the cost of a request matches what we actually spend serving it, so your contract goes further when you lean on cheaper-to-serve models.

## How your token contract maps to credits

Most contracts are denominated in tokens. The `/usage` page now expresses that allowance as credits, converted at the most favourable rate for you: **1 credit per 1,000,000 tokens** (the Align rate). A 10,000,000-token contract, for example, becomes a 10-credit allowance.

When you spend that allowance:

* **Align calls** cost 1 credit per million input tokens — exactly the rate at which your contract was converted, so your effective capacity matches your contract.
* **Lightning's cost-efficient variant** costs 1 credit per 2,000,000 input tokens — half the rate. A Lightning-heavy workload effectively gets up to 2× more capacity from the same contract.

If you've always used Align, your effective monthly capacity is unchanged. If you're using Lightning's cost-efficient variant, this is pure upside.

## Viewing your usage

The `/usage` page is scoped to one calendar month at a time. Pick the month from the dropdown in the top right; the current month is the default.

At the top, three status cards:

* **This Month** — credits consumed vs your allowance, with an overage indicator if you've gone over
* **Projected** — month-end projection based on your current pace, with an *on track* or *projected overage* status
* **vs Previous Month** — percentage delta vs the same point in the previous month, with both numbers spelled out so you can verify the math

Below the cards, a daily bar chart breaks down credit consumption by day and by model. A per-model table at the bottom shows requests, tokens, cached tokens, and credits for each model variant you've used this month — that's where you can see which models are driving your bill and how much caching saved you (see [Trace caching](/documentation/billing/caching)).

## What happens if you go over

<Note>
  Running out of credits doesn't block requests. Evaluation calls keep succeeding past zero; your `credits_remaining` simply goes negative and the page shows an overage indicator. If you persistently exceed your allowance, we'll reach out to talk about adjusting the contract — there's no automated cut-off.
</Note>

## Questions

Reach out to [support@composo.ai](mailto:support@composo.ai) — we're happy to walk you through your usage or talk about adjusting your contract.