Stamps.com cubic pricing is available by default for all ShipStation users creating labels in ShipStation with their Stamps.com account.
To receive cubic rates in ShipStation, make sure you do the following when you configure your shipment:
ShipStation will automatically apply the cubic rate whenever it's cheaper than the priority rate.
The process is slightly different if you are using the softpack option. Review the Stamps.com Cubic Pricing in ShipStation section of our Stamps.com integrations help article for more details.