USPS Flat Rate Boxes

How does one setup USPS Flat Rate Boxes in v3?

One of our products will fit in a USPS small flat rate box ($5.15).

Two to Four will fit in a USPS medium flat rate box ($10.50).

Larger products need large USPS flat rate box ($15.50).

Do I need to set this up using manual logic or is there a way to use the realtime USPS calculations?


I had kinda the same question, never got a response. Only wanted to allow certain amount of products per box, but never figured it out.

Depending upon your particulars, types of products, etc, you can try creating a few individual realtime shipping methods for your Priority Mail Flat Rate Boxes & naming them accordingly (Small Flate Rate Box, Medium Flat Rate Box, Large Flate Rate Box, etc) and use weight restrictions for each of these.

We set up the smaller flat rate boxes like this:

  1. We set it to where only packages under 1.5 lbs can ship
  2. We made the weight of products fit according to how many can fit in the small flat rate box. i.e. if the product is too large to go flat rate then we would make the weight 1.55 lbs. If I can get 4 of the items in the box then we would make them .33 lbs. While it may be slightly off the actual weight, this fits better for us to use smaller flat rate boxes.
  3. We don't try to break down the small flat rate box, flat rate envelope and flat rate padded envelop. We set one price for all three and then we make sure we set up products properly that we can fit into the flat rate boxes.

    I am guessing you can do the same thing with the larger flat rate boxes. The problem we have is we have so many various sizes we just could not go beyond the smaller flat rate shipping methods.