Create shipping classes to group products into brackets with similar weights and dimensions. You can assign different flat shipping rates for each class.
Use shipping classes to group products based on how much they cost to ship. Then, for each of your shipping zones, assign a different flat shipping rate to each class.
For example, you might have shipping classes for large and heavy products, small and lightweight products, and small but heavy products.
This article is divided into three steps:
- Create a new shipping class (this is the container into which you will group products)
- Assign products to your shipping class
- For flat-rate shipping, set up a special rate for your shipping class
1. Create a new shipping class
Navigate to Settings > Shipping and select Shipping Classes in the ribbon. Then select +Add Class.
Add a Name and short Description for the shipping class. You can input a Slug, or have one auto-generate by leaving the field blank. Click Save. 
2. Assign products to your shipping class
When you add a new product to your store, you'll have the opportunity to assign a shipping class.
To add a shipping class to an existing product, go to All Products and open the product you want to edit. Scroll down to Shipping and select an option from the Shipping Class dropdown.
Note: You can assign a product to only one shipping class, even if the product is variable.
3. Set up a special rate for your shipping class
Note: For this step, you'll need to have already set up your shipping zones.
- Go to Settings > Shipping and select Shipping Zones from the top ribbon.
- Click Edit under the zone you want to adjust.
- If you haven't yet enabled Flat-rate shipping for this zone, select it from the Shipping Methods dropdown and click +Add.
If you have already enabled Flat-rate shipping, you'll need to delete in and re-add it in order to sync it with your shipping classes. Just click Delete under Flat rate, then select again it from the Shipping Methods dropdown and click +Add.
Click Edit under Flat rate to bring up the Flat rate Settings popup. Under Shipping Class Costs, enter a rate for each of your shipping classes.
Use the No shipping class cost field to set the rate for products that do not have an assigned shipping class.
