When you create a shipping label you select the type of envelope or package for your shipment using the Choose Your Packaging screen.
Depending on the carrier and whether you are using carrier-specific packages (flat-rate envelopes or boxes) or your own packages, you may be prompted to enter the weight of your shipment. place the package on the weighing platform and click the scale button.
The weight will appear in the Weight field.
Refer to How to create a shipping label in SendPro™ 300 for more information.