USPS is a popular shipper and very easy to setup live shipping rates with your WP EasyCart ecommerce plugin.  Here we outlines the steps and the different ways to can engage and enable the USPS rate system.

How Live Shipping Rates Work

It is important to know how your ecommerce store handles live shipping rates so you have a clear understanding of what they CAN do and what they CAN NOT do.  Live rates will provide you with rates from the carrier based on specific data your site sends.  For example, when you create a product in EasyCart, you should assign it default package Length, Width, and Height dimensions as well as a Weight value.

WP EasyCart will use these to create a ‘best fit’ package and combined weight from the shopping cart of all shippable items and when a customer is checking out, it will send their ship-to postal code and your ship-from postal code to get rates.

What Live Shipping Rates Won’t Do

It is also important to know that live shipping rates stop there. They provide customer shipping rates directly from the carrier.  They do not submit a package or purchase shipping labels as part of a post-order fulfillment process.  The WP EasyCart Premium edition does offer several options to connect with providers who specialize in this, such as ShipStation or Stamps.com, where you can purchase actual labels and align what rate the user purchased vs actual label choices.

Live shipping rates is also limited in that it doesn’t receive discounted rates if you use a third party system such as shipstation, stamps.com, goshippo, pirateship, etc.

Setting Up USPS Live Shipping

WP EasyCart has made it easier to than ever to utilize USPS rates within our application.  In the past you would create your very own developer account and then create an app within USPS to acquire credentials.  This has been replaced with an easy ON/OFF system that will utilize the EasyCart USPS connected app for obtaining rates.

There are 3 ways to connect to USPS live rates:

1.  Enable USPS (recommended) – This will utilize EasyCart USPS app and no credentials are needed on your part.  Easiest method!

2.  Enter your own Credentials – Requires you setup a USPS developer account to obtain credentials.

3.  Revert to Webtools – This is the original fallback and previous system which continues to work until January 2026.

As of January 2026, the old method of connecting has been discontinued by USPS.  To get started, you will login to your WordPress and visit the WP EasyCart -> settings -> shipping settings.

Method 1:  EasyCart USPS connected app

Step 1:  Enable USPS

This is the recommended and easiest method and you simply  ‘Enable USPS‘ and enter your origin zip code which you will be shipping from.

As you can see below, you should see a green ‘connected‘ status light when it is successfully getting communications and rates from USPS.

This process uses our EasyCart USPS connected APP as a way to get rates without all the messy developer sign-up and API key process.

Proceed to Step 2 ->

Method 2:  USPS developer credentials & app

Step 1:  Enable USPS

If for some reason you wish to develop or attach USPS to your direct developer account, you will need to follow a series of steps in order to attain the proper Client ID and Client Secret.

Visit https://developer.usps.com and create an account for your site.  You will need to register with them on several levels and generate your Client ID and Secret.

It’s a good idea to follow their procedures on the USPS developer site here:  https://developers.usps.com/getting-started 

Once you have the Client ID and Client Secret, you can enter them here in our settings with ‘Enter your Own Credentials‘.

Proceed to Step 2 ->

Method 3:  Old Webtools Method

Step 1:  Enable old Webtools method

This method has been discontinued by USPS as of January 2026 but we have left it here as a backup in case their system continues to operate or keep it running.  This is their old webtools method of getting rates and requires you to obtain and request access to use USPS API rates. 

Visit:  https://www.usps.com/business/web-tools-apis/    You must create an account, register, and also email webtools@usps.gov and request API access to their webtools system.  You should have received a userid and MID via email during the registration process.

We may remove this section in the near future once we feel their new V3 system is smoothly operating.

Proceed to Step 2 ->

Step 2:  Setting up Individual Rates

Now that we are connected to a live carrier, we can setup which live rates we wish to show to our customers.  Just go to the WP EasyCart -> Settings -> Shipping Rates panel and we can engage ‘Live Shipping Rates‘ as our choice for store shipping.

Notice in this example, we have turned on ‘Live Shipping Rates’ at the top and it has pre-installed some Live Rates for us down below.  Here you may add to or remove rates based on your preference and situation.

You can also setup an override price, free shipping threshold as well as a zone to each shipping rate.

• Override Price:   This will simply make the rate show a set price you establish here.
• Free Shipping Threshold:  If you wish to have shipping be free on one special live rate when a value in the cart is reached, you may do so here.  For example…  $100 dollar orders or more qualify for free USPS ground shipping.  You can target that specific rate and value to achieve this promotion.
• Shipping Zones:  This needs to be used carefully.  Zones are simply a post-address filter and are not a way to limit shipping.  The API is smart, it will limit and only show the rate if it ships to that location.  We recommend you set this to ‘No Zone’ unless you explicitly know what you are doing.

Special Considerations:

It is important to understand how live rates work.  Just because you setup a shipping rate does not mean all customers will see them.  For example ground shipping to an island doesn’t work, or some locations never provide 2nd or next day air.  Some rates are specifically for international users, while shipping within the same city can also require special rates.

For this reason, we recommend you start out by adding as many of the rates and possible and testing it out on various important addresses and locations you plan to ship to.  Make sure ‘SOME’ of the rates return in each situation.  You may have 10 shipping rates setup in WP EasyCart, but a customer with a certain address may only see 2 or 3 of the rates due to their location and address!

Step 3:  Product Considerations

Now that you are connected, a couple checks are needed on your products to make sure they are shippable, have dimensions and weights, and will respond to live shipping calculations.  Go to the WP EasyCart -> Products panel and edit one of your shippable items.

In this example, we have edited a product and added weight and dimensions.  Note that the dimensions are excluded.  You may set ‘Standard’ or ‘Metric’ as your units within the WP EasyCart -> Settings -> Shipping Settings panel.  Standard units (lb/in) or Metric (oz/cm) are sent to carriers depending on your selection.

Notice that under the Shipping Options we also must ‘Enable Shipping‘ so this item will get into our calculation.   A neat feature in WP EasyCart is you can also add a handling fee that gets added to all the shipping rates.  Maybe you want an extra $5.00 for handling per item or just one time…  just enter your value here for this product.  You may add a global handling fee in our shipping settings panel as well as many other options!

Step 4:  Complete!

That’s it, you have successfully connected to and setup live shipping rates and your shopping cart will now pull shipping rates based on the total contents of shippable items within the customers cart.  Every order will show you the customers selected shipping choice AND what they paid for the shipping service.  You can now use any shipper service and pay for shipping accordingly.

Don’t forget, you can use WP EasyCart Premium to connect to various third party programs for actual post-order fulfillment and label purchasing!  Check out the PRO version which has live shipping rates + the Premium edition which offers live shipping AND connections to third party shipper services!

Video Resource:

We also have a video resource to see an overview of setting up live shipping as well within WP EasyCart