Medusa Quantity Pricing Rules

Medusa v2 plugin for quantity range pricing (volume / tiered / wholesale). Set unit prices by quantity with fixed prices, percentage discounts, or fixed amount-off tiers.

Watch demo: https://www.youtube.com/watch?v=CjBjc7j3H6g

Features

• PostgreSQL quantity_prices table (module + migrations)
• Pricing types: fixed, percentage, fixed_discount
• Admin API (CRUD + Zod validation) and Store API (list tiers, calculate price)
• Admin UI: Settings → Extensions → Quantity Pricing, per-product widget, store summary widget
• Workflows with compensation (create / update / delete)
• Auto cleanup on product.deleted
• Optional variant, region, and customer-group scoping
• Exported helpers: resolveQuantityUnitPrice, catalog utilities, workflows

Requirements

| Requirement | Version | |-------------|---------| | Node.js | 20+ | | Medusa | v2.13+ (@medusajs/framework ^2.13) |

Installation

npm install @webbycrown/medusa-quantity-pricing-rules

Register in medusa-config.ts:

import { defineConfig } from "@medusajs/framework/utils"

export default defineConfig({
  plugins: [
    {
      resolve: "@webbycrown/medusa-quantity-pricing-rules",
      options: {},
    },
  ],
})

Registers the pricingEngine module automatically. Do not add a duplicate entry under modules.

Run migrations and start Medusa:

npx medusa db:migrate
npm run dev

Open Admin → Settings → Extensions → Quantity Pricing to create tiers.

Admin UI

| Location | Purpose | |----------|---------| | Settings → Extensions → Quantity Pricing | List, create, edit, delete rules | | Products → [product] | Tiers for that product (product ID pre-filled) | | Settings → Store | Rule count + link to settings |

Tier fields

| Field | Description | |-------|-------------| | Product ID | Required (auto-filled on product page) | | Variant | Optional — empty = all variants | | Min qty | Minimum quantity (e.g. 1) | | Max qty | Upper bound; empty = open-ended (e.g. 51+) | | Pricing type | fixed, percentage, or fixed_discount | | Discount / unit price | See Pricing types | | Currency | ISO 4217, e.g. inr, usd | | List price (reference) | For discount tiers when catalog price is missing |

Non-overlapping ranges per product + currency are recommended. When ranges overlap, the tier with the highest min_qty that still fits the quantity wins.

Pricing types

| Type | price means | Resolved unit price | |------|----------------|---------------------| | fixed | Tier unit price | price | | percentage | Percent off catalog (e.g. 10 = 10% off) | base × (1 − price/100) | | fixed_discount | Amount off per unit | max(base − price, 0) |

base is resolved in order:

1. base_unit_price on Store API / resolveQuantityUnitPrice
2. Medusa variant catalog price for currency_code
3. reference_unit_price on the rule

Store API

GET /store/quantity-pricing — requires a publishable API key.

| Param | Required | Description | |-------|----------|-------------| | product_id | Yes | Product to load tiers for | | variant_id | No | Variant-specific rules + product-level fallback | | currency_code | No | Filter / calculation currency | | customer_group_id | No | B2B segment | | region_id | No | Regional override | | quantity | No | When set, includes calculated_price | | base_unit_price | No | Catalog price for discount tiers |

GET /store/quantity-pricing?product_id=prod_01XXXX&currency_code=inr&quantity=25

{
  "quantity_prices": [],
  "calculated_price": {
    "unit_price": 90,
    "quantity": 25,
    "currency_code": "inr",
    "rule_id": "qprice_02...",
    "pricing_type": "fixed",
    "line_total": 2250
  }
}

Without variant_id, only product-level tiers (variant_id = null) are returned.

Admin API

Authenticated admin session or token.

| Method | Path | Description | |--------|------|-------------| | GET | /admin/quantity-pricing | List rules | | POST | /admin/quantity-pricing | Create rule | | GET | /admin/quantity-pricing/:id | Get rule | | PUT | /admin/quantity-pricing/:id | Update rule | | DELETE | /admin/quantity-pricing/:id | Delete rule | | GET | /admin/quantity-pricing/catalog-prices | Variant catalog prices |

Create fixed tier:

{
  "product_id": "prod_01XXXXXXXX",
  "min_qty": 1,
  "max_qty": 10,
  "pricing_type": "fixed",
  "price": 100,
  "currency_code": "inr"
}

Open-ended tier (51+): set "max_qty": null.

Package exports

import {
  PRICING_ENGINE_MODULE,
  resolveQuantityUnitPrice,
  fetchCatalogPricesForProducts,
} from "@webbycrown/medusa-quantity-pricing-rules"

const unitPrice = await resolveQuantityUnitPrice(container, {
  product_id: "prod_01...",
  variant_id: "variant_01...",
  quantity: 25,
  currency_code: "inr",
  rule_id: "qprice_02...", // optional — pin selected tier
})

const pricingEngine = container.resolve(PRICING_ENGINE_MODULE)
const result = await pricingEngine.calculatePrice({
  product_id: "prod_01...",
  quantity: 25,
  currency_code: "inr",
})

import {
  createQuantityPricingRuleWorkflow,
  updateQuantityPricingRuleWorkflow,
  deleteQuantityPricingRuleWorkflow,
} from "@webbycrown/medusa-quantity-pricing-rules/workflows"

| Export | Purpose | |--------|---------| | PRICING_ENGINE_MODULE | Container key ("pricingEngine") | | pricingEngineModule | Module definition | | PricingEngineService | Service class | | resolveQuantityUnitPrice | Resolve tier unit price (cart / checkout) | | fetchCatalogPricesForProducts | Batch catalog prices | | getBaseUnitPriceForRule | Base price for a rule | | Types | QuantityPriceRuleDTO, CalculatePriceInput, PricingType, … | | ./workflows | Create / update / delete workflows |

The plugin does not modify cart line items automatically. Use resolveQuantityUnitPrice in your add-to-cart flow when a tier applies.

Tier matching

1. Load rules for product_id (+ optional filters).
2. Prefer variant-specific rules when variant_id is set.
3. Match min_qty ≤ quantity and (max_qty is null or quantity ≤ max_qty).
4. Highest matching min_qty wins.
5. Resolve unit price from pricing_type and base price sources.

Database

Table quantity_prices: product_id, variant_id, min_qty, max_qty, pricing_type, price, currency_code, reference_unit_price, customer_group_id, region_id.

After model changes in a fork:

npx medusa db:generate pricingEngine
npx medusa db:migrate

Troubleshooting

| Issue | Check | |-------|--------| | Admin page not found | Rebuild plugin (npm run build in package) and restart Medusa | | Empty quantity_prices on store | Rules exist for product_id + currency_code; pass variant_id if needed | | Wrong discount price | Variant catalog price or reference_unit_price; pass base_unit_price | | Wrong tier | Overlapping ranges — highest min_qty wins | | Module not found | Plugin under plugins in medusa-config.ts, not duplicated under modules |

Changelog

See CHANGELOG.md.

Author

WebbyCrown — [email protected] · webbycrown.com