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

# Volume

Select the volume charge model if you want to define several price tiers but
want to apply a **single unit price based on the total volume**. You can also
apply a **flat fee** in addition to the unit price.

Consider the following example, where each unit represents an API call:

| Tier   | First unit | Last unit | Unit price | Fixed fee |
| ------ | ---------- | --------- | ---------- | --------- |
| Tier 1 | 0          | 10,000    | \$0.0010   | \$10      |
| Tier 2 | 10,001     | 50,000    | \$0.0008   | \$10      |
| Tier 3 | 50,001     | 100,000   | \$0.0006   | \$10      |
| Tier 4 | 100,001    | ∞         | \$0.0004   | \$10      |

In this case, 65,000 API calls would cost 65,000 x \$0.0006 + \$10 = \$49.