SettingsVolume Pricing

Volume Pricing

Volume Pricing is the PromoSync feature that automatically discounts cart lines down to the matching tier price at checkout. It is powered by the Quantity Price Breaks Shopify Function, which reads each variant’s tier-price array (psrestful.part_price_array) and applies the correct unit price based on the quantity in the cart.

The display block on the product page (Volume Pricing Theme Extension) only shows the table of tier prices. This setting page controls the underlying Function that actually applies the discount.

The Two Settings

The feature is configured from two fields in Shop Settings.

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Screenshot needed: Shop Settings page showing the Enable Volume Pricing checkbox and the Mode dropdown. Save to /public/images/volume-pricing-settings.png.

Enable Volume Pricing

A single checkbox. Turning it on tells PromoSync to create an automatic discount in your Shopify store’s Discounts section, linked to the Quantity Price Breaks Function. Turning it off deletes that automatic discount so no tier-price discounting happens at checkout.

You don’t manage the discount in Shopify Admin directly: flip this checkbox and PromoSync calls the Discounts API to create or remove it for you.

Mode

A dropdown with two options. The mode controls how the Function groups cart quantities when it decides which tier each line qualifies for.

ModeWhat it doesWhen to use it
Per variantEach cart line’s quantity decides its own tier independently.You sell products where the customer is buying one variant at a time, or where mixing variants shouldn’t grant a higher-quantity discount.
Combined by productQuantities are summed across every cart line that shares the same parent product, and each of those lines gets the tier price for the combined total.The common case for apparel: the customer fills a cart with 4 Red, 4 Blue, and 4 Green of the same polo, hits the “12 piece” tier together, and every line gets the 12-piece price.

A Worked Example

Suppose a polo has tier prices: 1+ at $20, 12+ at $15, 24+ at $12. The customer adds 4 Red, 4 Blue, and 4 Green to the cart.

ModeRed line priceBlue line priceGreen line priceWhy
Per variant$20 (qty 4)$20 (qty 4)$20 (qty 4)Each line’s own qty of 4 is below the 12 tier.
Combined by product$15 (qty 4)$15 (qty 4)$15 (qty 4)Combined qty across the three lines is 12, so every line gets the 12-piece price.

Where to Find It

  1. Open PromoSync from your Shopify admin.
  2. Go to Shop Settings.
  3. Scroll to the Volume Pricing section.
  4. Tick Enable Volume Pricing and choose the Mode.
  5. Save.

The first time you save with Enable Volume Pricing turned on, PromoSync creates the automatic discount in your Shopify store. From that point, switching the Mode updates the discount’s configuration in place without recreating it.

Prerequisites

For the discount to actually fire on a line at checkout, the variant on that line must have a populated psrestful.part_price_array metafield. That happens automatically when:

  • The variant was imported from a supplier that publishes PPC tier data, or
  • The product carries a tag matched by an active Tier Pricing Rule.

Variants without tier data are simply ignored by the Function (no discount is applied to those lines). To re-populate the metafield after changing pricing rules, run Update Metafields on the affected products.

Verifying It Worked

After enabling the toggle:

  1. In Shopify Admin, open Discounts. You should see a new automatic discount named Quantity Price Breaks.
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Screenshot needed: Shopify Admin Discounts page showing the Quantity Price Breaks automatic discount listed and active. Save to /public/images/volume-pricing-discount-in-admin.png.

  1. Add a tier-priced variant to your cart at a quantity that crosses a tier breakpoint. The cart and checkout should show the discount as a line-level price reduction.
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Screenshot needed: Checkout breakdown showing the Quantity Price Breaks discount applied to one or more lines. Save to /public/images/volume-pricing-checkout-discount.png.

  1. To verify Combined by product mode, add multiple variants of the same product, each at a quantity below the next tier but with a combined total that crosses it. The checkout breakdown should show all of those lines getting the higher-quantity tier price.
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Screenshot needed: Checkout breakdown demonstrating combined-by-product mode (e.g. 4 Red + 4 Blue + 4 Green polos getting the 12-piece tier price on every line). Save to /public/images/volume-pricing-combined-by-product.png.

Why Both Modes Exist

The default Per variant mode is what you want when each cart line is its own thing: a unique decorated product, a custom-built bundle, or anything where the buyer is committing to a specific quantity of a specific variant.

Combined by product is what you want for apparel and similar categories where the buyer thinks of the product as one thing (a polo) and treats colors and sizes as splits of one order. Without combined mode, a buyer who orders 4 each of three colors would end up paying the 4-piece price on every line, even though the apparel supplier (and the buyer) consider that a 12-piece order.

The mode applies globally to your store. There’s no per-product override, so pick the one that matches the bulk of your catalog.

Caveats

  • Display block and Function read the same data. The product-page table and the checkout discount both come from psrestful.part_price_array, so they stay in sync. If you change pricing rules, run Update Metafields on the affected products to refresh both at once.
  • Don’t edit the discount in Shopify Admin. PromoSync owns the Quantity Price Breaks automatic discount. Editing its name, status, or configuration manually can desync it from the toggle. To turn it off, untick Enable Volume Pricing in PromoSync settings.
  • The Function only discounts; it never raises prices. If a variant’s listed Shopify price is already at or below the tier price for the cart quantity, the line isn’t touched.

Related

Tier Pricing RulesGuides Overview