Calculated Shipping not working - proper product weights but inconsistent billing rates

New Member
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I've never had a problem like this until now. All of my products have proper weights added, packaging sizes, as well as shipping zones. Shopify is automatically charging shipping amounts that are completely off, and undercharging customers costing me money. Examples:

  • 4 of Product X was $14.56 (which is about right)
  • 8 of the same product X and one of product Y (same weight) was $11.89 (the discount code takes off 50% of product Y)

Please let me know how to resolve this issue. This is costing me money on every single order that goes out like this. Screenshots are attached. Notice the order weightNotice the order weightThis one is more realisticThis one is more realistic


Shopify Partner
126 6 24

Hey @markiafrate,

When you noted that you have added the proper packaging size, it's important to note that Shopify only uses these sizes for fulfillment (when you ship the order). For your customer-facing calculations, they send off one box size, called your 'default box size'. Regardless of what is in the order, Shopify will select this box size for your live rate calculations. This is likely where your discrepancies are coming from. To add unlimited box sizes and charge your customers accurate live rates, you will need a third-party app. Smart Boxing was built to solve this exact problem, but please note that no third-party apps have access to Shopify's discounted rates. You can either add a % discount to get close, or use the shipping difference (which will always be in your favour) to add extras like candy, cute note cards, nicer packaging etc. 

You can book a demo by following this link, just note that the next available times are on Dec 1st since our team is working around the clock right now for Black Friday/Cyber Monday weekend, ensuring our users have a successful weekend. If you email our support at, you can ask any questions you may have in the meantime. The app comes with a 14-day trial, so you feel free to take it for a test drive


Warm regards,


Co-Founder / CEO @ Intuitive Shipping Inc.
Intuitive Shipping | Smart Boxing | Automate Shipping Profiles