I'm using Magento Community 1.9.2, I'm new at this and I want to set shipping properly with UPS and USPS. I've set weight along with length, width and height (these 3 are custom attributes) for each of my products and I can see that at shipping options only weight is taken in consideration for UPS and USPS.
I have products that fit in an envelope and products that fit in a box, so I can't charge standard flat rate.
My question is: what the measurement unit of UPS and USPS and what's the best way to setup this properly?
Thanks