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Full Knowledgebase Listing

USPS Real-time shipping - setup

[#32] Last update 31 May 2012

USPS (United States Postal Service) provides a real-time lookup facility which Kartris can use for shipping rates.


Real-time shipping is based on the weight of an order. It is therefore essential that your product versions have the weight correctly specified in pounds.

Step 1 - Register with USPS

Sign up for access to the USPS real-time rates service:


Some time afterwards you should receive account details from USPS. Initially these will be for testing; once your site is setup and working, you can email their customer support to grant you access to the live production server.

Important - please read USPS's terms of use, especially regarding using the account details on other web sites.

Step 2 - Activate USPS support in Kartris

USPS support needs to be setup and activated within Kartris. In the back end, go to 'Configuration > Payment and Shipping Gateways. Select to edit the USPS record. You should see the following:

The 'friendly name' fields can be set to 'USPS' or whatever name this payment system will be referenced by.

The 'UserID' is the one provided to you by USPS.

'Origination Zip' is the postal code of your location where the goods are shipped from.

'Status' controls whether this shipping method is available in Kartris or not. You can set it to 'TEST' during setup, and then later to 'ON'.

Step 3 - Select when/where USPS is used to calculation shipping

You should first go through and ensure you have set up locations and shipping (see section 4.3.3 of the Kartris User Guide PDF).

Once this is done, go to 'Regional Setup > Shipping' and click the 'Shipping Methods' tab. Add a new method called 'USPS'.

Click on the 'Rates' link on this new record. You can choose which shipping zones USPS will be available for. If you want all orders for this zone to be handled by USPS, check the USPS box on the 'All higher orders' line.

Because real-time shipping integrations with the banded system within Kartris, you have a lot of flexibility. You can for example:

- Set USPS shipping for one region (e.g. domestic) and another system like UPS for another region (e.g. Rest of World)

- Set USPS to handle orders up to a certain weight for one region, and then set fixed pricing for weights above this. This is useful if the shipping provider only supports weights up to a certain level.

Step 4 - Test

When you go through checkout, assuming you specify you are in a location that is covered by USPS shipping, you should be able to choose from the available options (with prices) and proceed to pay for the order.


Real time shipping makes certain assumptions; in particular that the dimensions of the items are not excessively bulky for the weight. So for example, very long and thin items, or very light but large items (such as a large empty box) may incur additional charges in practice. But for most items, the convenience of an online lookup should offset the occasional anomalies.

Further information:

USPS's documentation and other information is available here:


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