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

# Pricing models

Every pricing preset uses one pricing model. The pricing model determines how a rate is calculated from quantity: whether every unit costs the same, or the rate changes as quantity grows.

<CardGroup cols={3}>
  <Card title="Per unit" icon="ruler" href="/docs/20260301/pricing-models/per-unit">The system charges a single price for every unit of usage.</Card>
  <Card title="Volume" icon="boxes-stacked" href="/docs/20260301/pricing-models/volume">The system applies one rate to all units, based on which volume band the total usage falls into.</Card>
  <Card title="Tiered" icon="stairs" href="/docs/20260301/pricing-models/tiered">The system splits usage across tiers and charges each tier at its own rate.</Card>
</CardGroup>

## Comparing the three

| Aspect             | Per unit                                   | Tiered                                     | Volume                                      |
| ------------------ | ------------------------------------------ | ------------------------------------------ | ------------------------------------------- |
| Rate determination | The same rate for every unit, always       | Each portion gets its own rate             | Total quantity picks one rate for all units |
| Brackets           | None                                       | Yes                                        | Yes                                         |
| Invoice display    | Single line item                           | Multiple line items, one per tier consumed | Single line item (one rate)                 |
| Best for           | Simple linear pricing, no volume incentive | Progressive rates, usage-based incentives  | Bulk discounts, committed volume deals      |

Per unit is the simplest of the three and the baseline the other two are compared against. Tiered and volume both use brackets, but they resolve them differently: tiered splits usage across brackets so each portion is billed at its own rate, while volume finds a single bracket for the total quantity and bills every unit at that one rate. See [tiered: what tiered pricing is](/docs/20260301/pricing-models/tiered#what-tiered-pricing-is) and [volume: what volume pricing is](/docs/20260301/pricing-models/volume#what-volume-pricing-is) for that distinction worked through in detail.

Each pricing model page covers how it applies to point in time and period of time products, how to configure it, and its full field reference.