For any carrier, you can choose to use your own envelopes or boxes in which case you will be prompted to select the package type (box, envelope, or irregular packaging) and enter the dimensions and the weight. Place the package on the weighing platform.
The weight will appear in the Weight field. SendPro™ 300 (for shipping) will calculate and display the total postage required once you enter the mail class and any special services.
For detailed information on size and weight restrictions, contact your carrier.