> ## 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.
# Graduated
Select the graduated charge model if you want to define **several price tiers**.
This charge model allows you to apply a discount depending on the number of
units consumed. You can also apply a **flat fee** to an entire tier.
Let's take back the example of the API company. You could charge \$1 per unit for
the first 100 units (first 100 API calls), then \$0.50 per unit for the next 100
calls and finally, \$0.10 for any additional unit.
Please refer to the tooltip in the user interface for more information.
