Custom Calculation: Apply Non-Standard Shipping Calculations

Custom Calculation: Apply Non-Standard Shipping Calculations

Overview

With the Custom Calculation feature you may set up non-standard shipping calculations that go beyond standard per-item or per-order logic. It works by defining a custom item, a virtual unit derived from your products, and then charging a fixed rate per each custom item using the FPCI (Fixed Per Custom Item) algorithm in Table Rates or Shipping Rules.

Popular scenarios

  • Shipping rate per every "10 items"
  • Shipping rate per every "10 lbs"
  • Surcharge per every 5 specific items
AlertShipping Segment must be configured before setting up Custom Calculation. It defines which products the calculation applies to.

Custom Calculation: Configuration Steps

Info
Before you start: create a Shipping Segment for the products this calculation should apply to (e.g. "Toys", "Heavy Items").
  1. Complete Custom Calculation settings: store, algorithm and segment
  2. Use FPCI (Fixed Per Custom Item) in a Table Rates method or Shipping Rule: set the rate per custom item
  3. Optionally: add the Cart Custom Item Quantity condition for tiered pricing by custom item count
IdeaAfter you finish: test the rate at checkout or with our Test Your Rates tool and check the Activity Feed.

Step 1: Complete Custom Calculation settings

Go to Custom Calculation:
  1. Store. Select the store. Each store has one Custom Calculation configuration.
  2. Condition. Select an algorithm and the Shipping Segment that defines which products count:
    • Per Product. Each unit of a product that matches the segment counts as 1 custom item. Example: 3 units of a matching product = 3 custom items.
    • Per Cumulative Amount. Select a product attribute (for example, Quantity or Weight) and enter a value. Calcurates adds up that attribute across the products that match the segment and divides it by your value, rounding up. Example: Quantity, value 3. A cart with 4 matching units = 2 custom items.
  3. Optionally, click Add condition to count other products in a different way.
If no product matches the segment, the cart has 0 custom items and rates priced only with FPCI are not shown.


Step 2: Use FPCI in Table Rates Method or Shipping Rule

In the Table Rates method's Rate settings, select FPCI: Fixed Per Custom Item as the calculation algorithm and enter the cost per custom item in the Value field.


Step 3: Add Cart Custom Item Quantity Condition (optional)

In the Rate's conditions, a dedicated Custom Calculation section lets you restrict the rate to a range of custom item counts. This enables tiered pricing by order size.

IdeaUse this condition to set up tiered rates: e.g. $12.00/custom item for 1–2 custom items, $10.00 for 3–5, $8.50 for 6+. Each tier is a separate rate row with its own FPCI value and quantity range.