Wix Stores: Setting Up Real Time Shipping Calculation with USPS

7 min read
  • This feature is only available for merchants in the U.S selling in USD  (except Puerto Rico).
  • Rates calculated during checkout may vary from the final shipping rates determined by USPS.
Real Time Shipping Calculation allows you to charge customers a more accurate rate for shipping.
How do real time shipping calculations work?
The USPS calculator provides approximate, dynamically-calculated shipping rates based on the weight and dimensions of the order, and on the shipping cost to and from addresses. 
Is this an estimate or the actual shipping price?
The price is a close estimate, however, actual shipping costs may vary based on how you choose to ship the package - the actual package you use and the actual weight of your package as determined by the carrier. 
Do I have to ship with USPS?
No, USPS is used for calculation purposes only. The estimate is also what your customers are charged. When you actually ship orders, you are free to do so with any carrier you choose.
Rate adjustments:
If you ship using another carrier and the actual price ends up not being the same as the estimate, your customer is still charged the price shown to them using Real Time Shipping Calculations. To account for the difference, you can add a rate adjustment during setup to ensure that you cover your actual shipping expenses.
How do I choose which packaging to use for the purpose of calculations?
During setup, you are asked to choose your main package type. This package's details will be used to calculate the estimated shipping rates of all your deliveries, even though you may ship using other boxes (or use other carriers).  
Let's look at two examples: 
  • During setup, you chose the USPS Small Flat Rate Box and indicated that it can hold two items. A customer buys 3 items from your store. Shipping is calculated as though you ship it using 2 USPS Small Flat Rate Boxes. In actual fact, you may choose to ship the item in one Medium Flat Rate Box.
  • Most of your items are small enough to fit into a USPS Small Flat Rate box, but you do sell some larger items. In this case, you would still choose the USPS Small Flat Rate box during setup. To offset the higher shipping costs for your larger products, you might consider adding a Set Rate Adjustment during step 2 of the setup process. 
I ship using different sized boxes. Which should I choose as my packaging type?
We recommend you select the package you use most often. 
What is the difference between flat rate packaging and custom packaging?
  • Flat rate envelopes and boxes: When you select a USPS flat rate option, the price is calculated per package (whatever fits in the box). Product weight and destination do not factor into the price for domestic shipping.
  • Custom packaging: Choose the Custom option to calculate the price of delivery with a USPS envelope or box that is not a flat rate option or when you want to ship using any other type of packaging. Shipping costs are calculated based on package weight and customers' address.    
Not all shipping services are available for all packaging types. Check your carrier for details. If your shipping and packaging selections are not among the available options – Wix may offer the customer an alternative delivery method. As a result, applicable shipping cost may be adjusted. 
Want to learn more?
Check out the full Wix Learn course on getting started with Wix eCommerce. Skip to the fourth video to learn more about setting up shipping.

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