Use the quantityRuleCreate mutation to set minimum, maximum, and increment quantity rules on a product variant within a catalog context.
Provide a QuantityRuleInput with minimumQuantity, maximumQuantity (optional), and increment fields; these enforce ordering constraints at checkout for B2B buyers.
Add quantity price breaks via quantityPricingByVariantUpdate or by adding PriceListPrice entries with minimumQuantity thresholds to a price list using priceListFixedPricesAdd with quantity parameters.
Query the price list's prices with their minimumQuantity fields to verify tier pricing is correctly configured.
Test the resolved price in a B2B buyer session by adding the variant quantity that should trigger the break and checking cart.lines.cost.
Consult current Shopify B2B and price list documentation for whether quantity price breaks are configured at the price list level or via a separate quantity pricing feature.
Known gotchas
Quantity rules are enforced at checkout via Shopify's validation; however, the Storefront API cart does not always surface quantity rule violations as userErrors in real time—test the full checkout path.
Quantity price breaks and quantity rules are separate concepts and must be configured independently; having a minimum quantity rule does not automatically create tiered pricing.
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