US Postal Service

The USPS Rates add-on provides live shipping rates from the United States Postal Service using the USPS Web Tools API.


  • Uncompress the add-on files
  • Upload the folder (directory) and all its contents to your Shopp add-ons folder (directory) under: .../wp-content/shopp-addons

USPS Web Tools Account Registration

You will need to register for a USPS Web Tools account in order to get access to the Web Tools services.

  • Fill out the registration form completely to setup your Web Tools account.
  • You will be sent an email including your USPS Web Tools User ID and further instructions to switch your account to the production environment.

To use the production servers, email the USPS Internet Customer Care Center (ICCC). They will switch your profile to allow you access to the production server and will provide you with the production URLs.

The ICCC is staffed from 7:00AM to 11:00PM Eastern Time.

  • E-mail: []
  • Telephone: 1-800-344-7779

These values are automatically supplied by the addon when Shopp sends a shipping calculation request to USPS. Simply proceed to call or email USPS as instructed in the email, and ask them enable your account on their production servers.

The email from USPS appears to be asking for an API_Name and XML_String_containing_User_ID. It is not.

Shopp USPS Settings

  • Login to your WordPress Admin and navigate to ShoppSetupShippingRates
  • For the appropriate shipping method, select USPS Rates
  • Select all of the shipping services you wish to offer your customers and apply to your products
  • Enter your User ID – The USPS Web Tools User ID you received by email when you registered for your account.
  • Enter Your postal code – The postal code you will be shipping from
  • Click the Save Changes button to apply your changes.
  1. Fatal error: Declaration of USPSRates::calculate() must be compatible with that of ShippingModule::calculate() in /home/metaq864/public_html/ on line 20

    November 23rd   #

  2. Seeing this error when I click estimate shipping in my cart.


    USPS — Please enter the package weight.

    June 19th   #

  3. This means that you have not gone through the products in your catalog and added weight to them. The products in your catalog need a weight assigned so that it can be passed to USPS to get an estimate.

    July 5th   #

  4. This plugin doesn’t do anything.

    I followed directions for installation. THREE TIMES.

    Plugin does not appear in “plugins”.
    Plugin does not appear at all.
    There are NO changes appear in Shopp → Setup → Shipping → Rates
    (neither plugin nor any indication of it appears here, either)

    Further, under Shopp → Setup → Shipping → Rates
    … the option for Flat Order Rates does not work. It does not matter what I put in there it charges NOTHING for Flat Order Rate.

    January 10th   #

  5. This is an add-on, not a plugin. It can not be installed as a plugin. You will need to upload the file(s) to the /wp-content/shopp-addons/ folder. Create the folder in case it is not present.

    March 28th   #

  6. When you purchase this program, does it expire and do you have to repurchase?

    January 16th   #

  7. The add-on will still work after a year, and can even be used on multiple websites.
    To have access to support and updates, after a year, you will have to repurchase.

    March 28th   #

  8. Good morning,

    Currently customers are placing an order the shipping is not calculating correctly. I would like for our customers to have the options to choose between shipping vendors ex. UPS, FEDEX, USPS or DHL to see what is cost effective. My question, do I need to purchase shipping add-ons for each? Please advise.

    May 17th   #

  9. If you want to offer live shippingrates from different couriers, you will have to buy the add-on for each carrier.

    April 7th   #

  10. I also would like to include Canada post as well. Occasionally there Canadian’s that purchase our materials as well..

    May 17th   #

  11. There is a Canadian Post add-on as well

    March 28th   #

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