How to combine Shopify shipping rates with rate blending

Updated July 20, 2026 · SMART Shipping Rates (E-TRADE PARTNER)

Rate blending combines multiple calculated Shopify shipping rates into one checkout method, so customers see a clean final price. SMART Shipping Rates & Rules supports combined rates using sum, cheapest, most expensive, or average logic. Because blended rates are calculated rates, Shopify Carrier Service is required for them to show at checkout.

Rate blending solves a common mixed-cart problem. One rule prices a heavy item, another prices a destination surcharge, and another handles a product fee. Without blending, the customer may see several delivery lines and wonder which one to choose. With blending, those parts can become one clear checkout method.

The goal is not to hide complexity from your team. The goal is to keep the rule logic visible inside the app while making the checkout simple for the customer.

Why combined rates matter

• They prevent customers from choosing only one part of a multi-part shipping cost.
• They make mixed carts easier when different products trigger different rates.
• They support surcharge-style setups without cluttering checkout.
• They help multi-rule stores keep one customer-facing delivery method.

What Shopify can and cannot do natively

Shopify can show rates from shipping settings and eligible apps, but it does not always combine custom logic the way a merchant expects. If several rules produce rates, the checkout may show multiple options. SMART Combined rates gives you control over how those matching rates become one amount.

Setup steps in SMART Shipping Rates & Rules

1. Create the individual calculated rules in Shipping rates, such as a base zone rate, product surcharge, or weight tier.
2. Open Combined rates and create a new combined rate rule.
3. Choose which rates should be included in the blend. Use clear internal names so you do not combine unrelated rates by mistake.
4. Select the blend method: sum, cheapest, most expensive, or average.
5. Set the customer-facing method name that should appear at checkout.
6. Open Shipping rates and check the Carrier Service notice if zone creation is disabled. Combined rates are calculated rates and need Carrier Service.
7. Test carts that trigger one included rate, several included rates, and no included rates.

Worked example: base rate plus remote surcharge

A merchant sells outdoor gear across Australia. Most orders use a base weight rate. Remote postcodes add a destination surcharge because the final delivery cost is higher. The merchant does not want customers to see Standard shipping and Remote surcharge as two separate choices.

1. Create a base calculated rate in Shipping rates using weight tiers.
2. Create a second calculated rate for remote postcodes.
3. Open Combined rates and include both rates.
4. Choose sum so the final checkout amount is base rate plus remote surcharge.
5. Name the result Standard delivery so the customer sees one method.

This is also useful for mixed carts where one product needs a per-item fee and another product follows the base rate. Instead of asking the customer to pick between partial prices, SMART can combine the components.

Practical blending tips

• Use sum for surcharges and additive costs. It is the easiest to explain to support.
• Use most expensive when the safest price should win for mixed carts.
• Use cheapest only when you are comfortable with the lower matching rate covering the shipment.
• Avoid average unless the matching rates are designed for that behavior.
• If the issue is only method order or wording, use hide, sort, and rename instead of blending.

How to keep blended rates auditable

Use internal names that state the purpose of each component, such as Base AU weight rate, Remote postcode surcharge, and Fragile product fee. Then name the combined customer-facing method simply. Your team should be able to open an order, recreate the cart, and understand why the blended price appeared.

Frequently asked questions