Here you will learn how to set up your shipping boxes.
Step-by-step guide
Login to your administration panel admin.yourwebsiteaddress.com
Click "Shipping" on the left hand navigation
Click "Shipping Boxes"
Select a box size from the drop down menu
Width - Box width (in inches)
Height - Box height (in inches)
Length - Box length (in inches)
Max Weight - The maximum weight of this size of box (in pounds.)
Remember that you must make these as accurate as possible in order to avoid mischarging by Shipping Provider