USPS Shipping

USPS is a built-in shipping method that calculates real-time shipping rates at checkout using the USPS REST API. No API key or USPS account is required — rates are pulled automatically based on package weight, dimensions, and destination.

Before you start

  • All products using USPS must have weight and dimensions (length, width, height) set. USPS cannot calculate rates without this information. If a product is missing weight or dimensions, customers will see an error at checkout.
  • You need your origin zip code (the zip code you ship from).
  • Your store address should be configured in Dashboard > Settings > Store Settings.

Setting up USPS

  1. On the Dashboard, go to Settings > Integrations > USPS
  2. Enter your Zip Code in the Ship From Location section. This is the zip code you ship packages from.
  3. Under USPS Services, check the domestic services you want to offer:
    • USPS Ground Advantage — Affordable ground shipping, typically 2–5 business days
    • USPS Priority Mail — 1–3 business day delivery
    • USPS Priority Mail Express — Overnight to 2-day guaranteed delivery
    • USPS Media Mail — Economical option for books, CDs, DVDs, and other media
  4. Under USPS International Services, check any international services you want to offer:
    • First-Class Package International Service
    • Priority Mail International
    • Priority Mail Express International
    • Global Express Guaranteed
  5. Click Save

Additional options

Local Pickup

Check Allow Local Pickup to add a free “Local Pickup” option at checkout alongside USPS rates. This is useful if you have a studio or shop where customers can pick up orders in person.

Discounted Commercial Rates

Check Discounted Commercial Rates to show USPS commercial pricing instead of retail rates. Commercial rates are discounted shipping rates for businesses with high shipping volumes. They are typically lower than retail rates. If you’re unsure, leave this unchecked to show standard retail rates.

Description

You can add a Description that appears on product pages next to the shipping rate (e.g., “Ships via USPS from Portland, OR”). To display this, enable Show Shipping rate descriptions on product pages in Dashboard > Settings > Design > Store.

How rates are calculated

When a customer enters their shipping address at checkout, IndieMade sends the package details to USPS and displays the available rates. The system automatically:

  • Calculates dimensional weight (length × width × height ÷ 166) and compares it to the actual weight. USPS charges based on whichever is greater.
  • Rate-shops cubic pricing for Ground Advantage and Priority Mail. Cubic pricing charges by volume and zone instead of weight, and is often cheaper for small, heavy packages. IndieMade automatically compares both rates and shows customers the lower price.
  • Uses the largest product’s dimensions in a multi-item order for the package dimensions, and adds up the total weight of all items.

Product requirements

Every product using USPS shipping must have:

  • Weight: The shipping weight of the product (must be greater than zero)
  • Dimensions: Length, width, and height (all three must be greater than zero)

Set these on each product’s edit page under the Shipping section. If any product is missing weight or dimensions, the customer will see an error message at checkout and will not be able to complete the order.

Important notes

  • No API key needed. Unlike Shippo and ShipStation, USPS rates are pulled through a free public API. There is nothing to sign up for or configure on the USPS website.
  • Domestic and international. USPS supports both U.S. domestic and international shipping. Enable the services you need in the settings.
  • Accuracy with multiple items. Since packing may vary, shipping costs may not be perfectly accurate when multiple products are purchased together. Test your shipping charges with sample orders and contact support if you notice issues.
  • Media Mail restrictions. Media Mail is only for certain items (books, sound recordings, recorded video, educational materials). Using it for non-qualifying items may result in postage due or returned packages.
  • Can be used per-product. If your store uses per-product shipping, you can assign USPS to specific products while using other methods (like Simple Shipping) for others.