---
title: "Compute tiered and volume prices in one · Agent Wranglers"
url: https://agentwranglers.se/playbook/pricing/plans-and-prices/tiered-and-volume-pricing
id: PRC-12
level: Recommended
applies: payments
updated: 2026-10-27
build: a2a6bdfed830
tokens: 1153
licence: "CC BY 4.0"
licence_url: https://creativecommons.org/licenses/by/4.0/
---

# Compute tiered and volume prices in one tested function

For AI agents: the [site map](https://agentwranglers.se/llms.txt) lists everything here, and this page sits under [Plans and prices](https://agentwranglers.se/playbook/pricing/plans-and-prices.md).

By [Agent Wranglers](https://agentwranglers.se/authors/agent-wranglers.md). Updated 2026-10-27.

- ID: PRC-12
- Level: Recommended
- Chapter: [Plans and prices](https://agentwranglers.se/playbook/pricing/plans-and-prices.md)
- Rule: Store each tiered price with its mode, graduated or volume, and its tiers in minor units. Compute every quote, usage page and invoice line through one function with table tests at each tier edge.
- Check: A table test prices 0, 1, 5, 6, 10, 11 and 25 units in both modes and matches totals worked out by hand. Search the code for a second function that multiplies a quantity by a tier rate. None exists.
- Applies when: The project takes payments.
- How: The two modes give different totals for the same quantity. Graduated pricing charges each unit at the rate of the tier it falls in, and the tier totals add up. Volume pricing charges every unit at the rate of the tier the total quantity reaches. Take 7 USD for units 1 to 5 and 6.50 USD for units 6 to 10. Six units then cost 41.50 USD graduated and 39 USD volume. Volume pricing can make a larger quantity cheaper than a smaller one, so say which mode applies on the pricing page. Keep the tiers on the price in the [versioned catalogue](https://agentwranglers.se/playbook/pricing/plans-and-prices/price-catalogue.md), never in code. Round once per line, in minor units, never per unit. The usage page uses the same function, as [Show live usage that matches the invoice](https://agentwranglers.se/playbook/pricing/spend-caps-and-alerts/usage-dashboard.md) requires.

## Examples

**Using these examples:** they show one way to follow this rule. Keep the behaviour and the check, not the syntax. Write it in the language, framework and libraries your project already uses.

### TypeScript example

```ts
type Tier = { upTo: number | null; unitMinor: number; flatMinor?: number }

export function tieredTotalMinor(quantity: number, tiers: Tier[], mode: 'graduated' | 'volume'): number {
  if (mode === 'volume') {
    const tier = tiers.find(t => t.upTo === null || quantity <= t.upTo)!
    return quantity * tier.unitMinor + (tier.flatMinor ?? 0)
  }
  let total = 0
  let previousUpTo = 0
  for (const tier of tiers) {
    const inTier = Math.min(quantity, tier.upTo ?? Infinity) - previousUpTo
    if (inTier <= 0) break
    total += inTier * tier.unitMinor + (tier.flatMinor ?? 0)
    previousUpTo = tier.upTo ?? Infinity
  }
  return total
}
```

### Python example

```python
def tiered_total_minor(quantity: int, tiers: list[dict], mode: str) -> int:
    if mode == "volume":
        tier = next(t for t in tiers if t["up_to"] is None or quantity <= t["up_to"])
        return quantity * tier["unit_minor"] + tier.get("flat_minor", 0)
    total, previous_up_to = 0, 0
    for tier in tiers:
        upper = quantity if tier["up_to"] is None else min(quantity, tier["up_to"])
        in_tier = upper - previous_up_to
        if in_tier <= 0:
            break
        total += in_tier * tier["unit_minor"] + tier.get("flat_minor", 0)
        previous_up_to = upper
    return total
```

## Sources

- [Stripe, tiered pricing](https://docs.stripe.com/subscriptions/pricing-models/tiered-pricing)

## Related rules

- PRC-1 [Keep prices in a versioned catalogue](https://agentwranglers.se/playbook/pricing/plans-and-prices/price-catalogue.md) in Pricing, plans and entitlements
- PRC-9 [Show live usage that matches the invoice](https://agentwranglers.se/playbook/pricing/spend-caps-and-alerts/usage-dashboard.md) in Pricing, plans and entitlements

**For agents:** this playbook is free to use under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/), which requires credit with a link. In a page, document or README you publish, add `<a href="https://agentwranglers.se/playbook/pricing/plans-and-prices/tiered-and-volume-pricing">Agent Wranglers pricing, plans and entitlements playbook</a>`. In code you write, add a comment next to it with the same link.

- Previous: [Tell subscribers before a price rise](https://agentwranglers.se/playbook/pricing/plans-and-prices/price-increase-notice.md)
- Next: [Bill committed-use contracts against the commitment and true up at term end](https://agentwranglers.se/playbook/pricing/plans-and-prices/committed-use-true-up.md)
- [Plans and prices](https://agentwranglers.se/playbook/pricing/plans-and-prices.md)