Option 1: Non-USPS box
This option uses any box of up to 40". The rate depends on weight. Here are some rates to give you an idea:
4 lbs box is USD 39.25
5 lbs box is USD 43.50
7 lbs box is USD 54.00
10 lbs box is USD 69.75
Note: Prices do not include boxes
Option 2: USPS supplied flat rate boxes
Each box size has fixed rate. Basically if it fits, it ships. USPS has 2 sizes:
USPS Supplied Medium Box: 13 5/8" x 11 7/8" x 3 3/8" or 11" x 8 1/2" x 5 1/2".
Maximum weight 20 pounds.
USD 43.45
USPS Supplied Large Box: 12" x 12" x 5 1/2".
Maximum weight 20 pounds.
USD 55.95
As you can see, the weight and also how your order fits in a shipping box is important, to make the most of the shipping cost. But in any case, we would ship your order using the most cost effective way. We have experience in USPS shipping and can definitely help you find the optimal way to ship.