If you have standard box sizes that you use repeatedly when fulfilling orders, you should set them up as Box Sizes in Cohub. This will save you from having to manually enter dimensions when creating packages.
Setting up a Box Size is simple. Navigate to Box Sizes in the Shipping submenu of the Settings menu:
Click the "New Box Size" button, and give your Box Size a name, dimensions, and maximum weight.
A Box Size's maximum weight is used to accurately retrieve Shipping Rates for Packages.
If you use a Carrier's Predefined Box Sizes, such as USPS Regional Rate Box A, you do not need to set those up as Box Sizes in Cohub. They are included as default options when you go to create a Package.