I created this to determine how to ship correctly, saving money, and not risking losing money on shipping.
It’s pretty dense with information, but once you learn it, saves some time. It’s also a learning aid.
The postal rate grid is broken up by two color fields, and a big white area to the lower right. The color areas are where the flat rate priority mail box is cheaper than using the measured rates, if you can fit the item into the box.
For first class retail parcels, flat rate is usually cheaper. For parcel select, there’s more areas where PSG is cheaper.
The white area is “no mans land”. It’s where the most expensive Flat Rate box is cheaper than measured rate.
I hope you enjoy the cheat sheet.