FedEx International Priority Flat Rate Boxes
Posted by Doug Sherman (Import), Last modified by Doug Sherman on 28 Dec 14 12:23 PM

FedEx International Priority Mail offers Flat Rate pricing (using their boxes) that can be a major savings over their normal calculated rate. The flat rate varies depending on the destination, but your package to that destination will cost the same regardless of its weight (up to the weight limit for the box); the only qualification is that your item/s can fit into one of their two flat rate boxes.


AuctionInc will determine the rate for your package based both on the flat rate (if qualified) and on the calculated rate, and display whichever rate is the less expensive.

By selecting this option, the shipping calculator will offer the appropriate flat rate price for International Priority Mail if all of the following conditions are met, once our packaging engine has created packages for all the items in the cart:


  • You have listed dimensions for all the items in the package
  • The dimensions of the package fit into dimensions of one of the flat rate boxes (see below)
  • The package does not exceed the flat rate box weight limit
  • The flat rate is less than the calculated rate.

The flat rate boxes are available in two sizes:

  • 10 KG Box
    15.81 x 12.94 x 10.19 inches
    22 LB weight limit (including weight of empty box: 1.94 LB)


  • 25 KG Box
    21.56 x 16.56 x 13.19 inches
    55 LB weight limit (including weight of empty box: 3.56 LB)



Prices for the boxes varies depending on the destination country.

When our packaging engine determines if the items in the cart/shipment can fit into one of these boxes, if it is dealing with a single item only, it simply checks the item dimensions against the FedEx-provided dimensions of each box. However, when dealing with multiple items or quantities, our packaging engine uses an overall volume figure rather than specific dimensions. Specifically, the FedEx box dimensions are multipled to determine initial volume, and then a "loss factor of 15 percent is factored in to take into account pack materials and packing inefficiencies. Both the largest and smallest of all the item dimensions in the cart/shipment are checked, and the total item volume is compared against our dervived box volume as indicated in the following table.


Box TypeVolume used for multiple items
(cubic inches)
10 KG Box 1765
25 KG Box 3465


Determining if a Flat Rate Box was Priced

If you are subscribed to our ShopCart, your customer has selected FedEx International Priority Mail, and at least one package in the order qualifies for one of the above flat rate boxes, you will see either "10KG" or "25KG" in our shipping "item" in your PayPal or Amazon order detail.

If you are subscribed to one of our extension modules, this code will appear in your packaging data in your order. And in our Shipping Rates API, the code is passed back in the FlatRateCode field.

(902 vote(s))
Not helpful

Comments (0)