How Product Group rates are calculated

Learn how rates are calculated when using Product Groups and tips and advice on the best way to set up your rates.


Postcode Shipping follows a similar approach to Shopify when calculating rates across Product Groups. Understanding this approach will help greatly when creating rates so we recommend reading this guide before getting started.

If you are in a hurry though try to remember these two key points when setting up your rates:

Rate titles matter

Try to reuse the same rate titles across Product Groups. If your ‘General’ Product Group contains a rate called “Fast shipping”, your “Heavy items” Product Group should also contains a rate called “Fast shipping”. These titles should match exactly (including casing). If rates do not have matching titles across groups, the cheapest rates from each group are returned with the name “Shipping”.

All Product Groups should have at least one rate in all Regions

If a customer checks out with an item in their cart that belongs in a group that you have not set up any rates for, we will be unable to quote for that cart and they will not get any rates from Postcode Shipping. You should ensure that if you want to ship all products to customers in a Region you have set up that there is at least one valid rate in every Product Group.

How rates are calculated

When Shopify sends information to Postcode Shipping we first determine which Shipping Zone and Region to use. If a Region you have set up is a match we then evaluate which Rates in that Region should be displayed.

If Product Groups are in use then the rates that are returned to customers will depend on the items in their cart and the rates that have been set up. Let’s look at an example:

Acme Inc. sells widgets. In Postcode Shipping they have two Product Groups set up:

  • “Fragile Items” - This Product Group contains all glass widgets.

  • “Heavy Items” - This Product Group contains all iron widgets.

There is also a default ‘General’ Product Group that contains all their other standard widgets.

Acme Inc. have a single Shipping Zone (Australia) and a single catch-all Region (Nationwide Shipping). Within this Region they have created rates in each of their Product Groups:

  • “General” has a “Fast Shipping” rate ($10) and “Standard Shipping” rate ($8)

  • “Heavy Items” has a “Fast Shipping” rate ($18) and “Standard Shipping” rate ($14)

  • “Fragile Items” has a “Courier Shipping” rate ($20)

Let’s look at how Postcode Shipping will quote depending on what is in a customer cart.

Scenario 1 - All cart items are in the same Product Group.

If the customer has a cart containing only standard widgets they will see only the rates the “General” Product Group:

  • Fast Shipping - $10

  • Standard Shipping - $8

This would be similar if the cart only contained iron widgets (the customer would see “Fast Shipping” - $18 and “Standard Shipping” - $14) or if the cart only contained glass widgets (the customer would see “Courier Shipping” - $20)

Scenario 2 - Cart items are in different Product Groups with rates that have the same titles

If a customer cart contained a standard widget and an iron widget then the customer would see the following rates:

  • Fast Shipping - $28

  • Standard Shipping - $22

The titles of these two rates are identical between the “General” and “Heavy Items” Product Groups. Therefore the rate price for each matching rate is added together to provide a combined total for each rate:

  • Fast Shipping (General) $10 (+) Fast Shipping (Heavy Items) $18 (=) Fast Shipping - $28

  • Standard Shipping (General) $8 (+) Standard Shipping (Heavy Items) $14 (=) Standard Shipping - $22

Note that if rates with matching titles are found across relevant Product Groups, any non-matching rates will be discarded. So if there was also a rate in the “General” Product Group called “Slow Shipping” that would not be displayed in the scenario above.

Scenario 3 - Cart items are in different Product Groups with rates that do not have the same titles

If a customer cart contained a widget of each type (standard, glass and iron) then they would see only one rate:

  • Shipping - $42

The reason for this is due to the fact that there is no rate that has the same title across all three Product Groups. In this situation, the cheapest rate in each group is selected, the prices are added together and a single rate with the title “Shipping”:

  • Standard Shipping (General) $8 (+) Standard Shipping (Heavy Items) $14 (+) Courier Shipping (Fragile Items) $20 (=) Shipping - $42

Scenario 4 - Cart items are in different Product Groups and one of these Product Groups contains no eligible rates

Acme Inc. add a rate rule to their “Courier Shipping” rate that prevents it from showing for orders under $100.

A customer cart again contains a widget of each type (standard, glass and iron) and the cart total is $50. In this scenario the customer would not see any rates.

This is due to there being no eligible rates for an item in cart (the glass widget). In order to provide a valid shipping quote, all cart items need to be ‘covered’ by a rate. As a result, extra care should be taken when setting rate rules to ensure that there are no gaps in the rules that would prevent a rate from being quoted in a given Product Group.


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