When customers add the same product variant to their cart with different customisations, Shopify creates separate cart lines for each one.
For example, a customer ordering three personalised mugs, each engraved with a different name, will see three separate lines in their cart.
The "Combine lines of the same variant" setting allows MNML Volume Pricing to count these quantities together when calculating volume discounts and minimum purchase quantities.
Imagine you've configured the following volume pricing tiers for a personalised mug:
Quantity | Price per mug |
|---|---|
1+ | £15.00 |
3+ | £12.00 |
5+ | £10.00 |
A customer adds:
1 mug engraved with "James"
1 mug engraved with "Sarah"
1 mug engraved with "Daniel"
Although these appear as three separate cart lines, they're all the same Shopify variant.
With "Combine lines of the same variant" enabled, their quantities are counted together. All three mugs qualify for the 3+ tier at £12.00 each.
With the setting disabled, each line is calculated separately, so none reaches the 3+ tier.
This setting also works with "Enforce minimum quantity".
For example, if you've set a minimum quantity of three mugs, customers can purchase three separately personalised mugs to meet that minimum.
The minimum is enforced against the combined quantity at checkout, rather than requiring three of each personalisation.
This is particularly useful for products with line item properties, including:
Personalised gifts and engraving
Custom-printed products
Products with customer-entered text
Made-to-order items with customisation options
Important: This setting only combines cart lines belonging to the same Shopify variant. It doesn't combine different variants or different products.
To combine quantities across different variants, see "Combine Variants for Volume Pricing". To combine different products, use Mix & Match within Pricing Rules.
