When a customer purchases an item from your store, you can offer them multiple shipping options
To add a shipping option:
This button will show the settings for Name, Destination, Courier, Estimated delivery time and shipping cost.
If the cost of shipping varies by weight, toggle Apply rate based on weight
The default unit for weight is grams. This can be changed to kilograms, pounds or ounces. Go to Store settings and select the Currency & Formats tab.