U.S.P.S. Online Rate Calculation (Domestic & International)

Important USPS Integration Update – Action Required by January 25, 2026

If you currently use Miva’s USPS integration module for shipping rates or address validation, you must install this update by January 25, 2026, to avoid service disruptions. USPS is retiring its current rates API platform on that date. This updated integration ensures continued compatibility with USPS’s new API for both shipping and address validation services.

We recommend updating as soon as possible to ensure uninterrupted USPS service.

Setting Package Dimensions and Weight

Important: If package weight or dimensions are set to zero, USPS shipping rates will not calculate correctly. Ensure fallback package settings are configured as described below.

• Package Dimensions must be set to greater than 0 × 0 × 0 inches

• Package Weight must be set to greater than 0

Update Package Dimensions:

PATH: Settings > Shipping Settings > Settings Tab > Packaging Rules Section. Fallback Package Dimensions 

1. Navigate to Settings → Shipping Settings

2. Open the Settings tab

3. Locate the Packaging Rules section

4. Configure the Fallback Package Dimensions and package weight values.

Package weight is derived from one or more of the following:

1. Product Weight: Each product a weight greater than 0. This can be set on the Product page or by importing product information.

2. Inventory Variant Weights (if applicable): If you use variants or inventory parts, their weights must also be greater than 0, depending on your Inventory Variant Handling settings. 

3. Box Weight (Pack by Weight): When you add a box, set the box weight to greater than.

For detailed configuration instructions, refer to the Shipping Settings documentation.

For detailed instruction on adding boxes, refer to the Boxes documentation.

For detailed instruction on Importing Product details, refer to the Data Import/ Export documentation.

On Getting Shipping Rates from U.S.P.S. 

You can use this module to get rates for U.S.P.S. shipping and to print address labels, but you cannot use this module to print U.S.P.S. postage. If you want to print address labels with U.S.P.S. postage, you have two choices:

• Use the U.S.P.S. Online Rate Calculation module to get shipping rates. Use the Endicia module to print address labels with U.S.P.S. postage. This is the easiest method and the one that most merchants choose.
• Use the U.S.P.S. Online Rate Calculation module to get shipping rates and to print address labels. Use an external method, such as a postage meter or stamps, to add U.S.P.S. postage.

U.S.P.S. Online Rate Calculation module can use all of the features from the Miva Shipping Settings feature.

Step 1: Install the U.S.P.S. Online Rate Calculation (Domestic & International) Module

Go to PATH: Settings > Shipping > Add / Remove Modules > Available Modules section or search U.S.P.S in the module search bar

1. Click Install under U.S.P.S. Online Rate Calculation (Domestic & International).
2. After installation the window opens to the U.S.P.S. Online Rate Calculation (Domestic & International) page under the Shipping Settings page.

Reminder: Package dimensions must be set to greater than 0x0x0in and Package Weight must set to greater than 0 for USPS module to calculate rates properly.

Update Package Dimensions: go to PATH: Settings > Shipping > Settings Tab under the Packaging Rules section, Box Packaging set to Always Use the Fallback Package Dimensions these dimensions must be greater than 0x0x0in. 

Update Weight: The weight is located on the product page of an item. PATH: Catalog > Product for instructions on exporting products from your store to do a bulk update see the Import/ Export Data Management documentation Here.

Step 2: Migrate Legacy U.S.P.S Settings

PATH: Settings > Shipping Settings > U.S.P.S. Online Rate Calculation (Domestic & International)

To migrate legacy U.S.P.S Settings click on the ellipsis (...) located at the top of the page, next to the Add/Remove Modules Button, then Click on Migrate Legacy U.S.P.S Settings. 

Important Notes:

1. The Legacy U.S.P.S. Online Rate Calculation (Domestic & International) tab must be active to Migrate the Legacy Settings to the new module.
2. You need be on the new Module U.S.P.S. Online Rate Calculation (Domestic & International) tab for the Legacy Settings Migration option to be visible.

Step 5: Deactivate the Legacy U.S.P.S Module

Notice: After you install the new Module and return to the Shipping Settings page you see both the new U.S.P.S and Legacy U.S.P.S modules in the more dropdown or on the tab menu bar. 

To deactivate the legacy U.S.P.S, go to PATH: Settings > Modules, find the module you want to uninstall, click the ellipsis menu ( ... ) next to the Installed indicator, and choose Uninstall.

Note: When you click the uninstall button on a Module associated with unbatched orders you will get a strongly worded pre-removal warning detailing the consequences of removal.