A merchant needs to automatically assign different box sizes based on order quantity to calculate accurate shipping costs. Currently, Shopify only allows setting one default box size, which causes problems:
The Issue:
Orders of 1-2 items ship fine in the default box
Orders of 5+ items require a larger box, leading to undercharged shipping costs
The merchant either loses money on shipping or risks cart abandonment from overcharging
Proposed Solution:
A third-party app (Multi Carrier Shipping Label) was recommended that:
Allows setting up multiple package sizes based on product dimensions and weight
Automatically selects the appropriate box and calculates rates accordingly
Offers a 14-day free trial
Current Status:
The discussion remains open with another user experiencing the same limitation. No native Shopify solution exists yet for conditional box selection based on item quantity.
Summarized with AI on November 16.
AI used: claude-sonnet-4-5-20250929.
I am struggling to find a way to set up a logical shipping rule that would say “If a customer orders 3 items, THEN use this box for shipping costs” and “IF a customer orders 10 items, THEN use this box for shipping costs.” etc.
I only sell 3 items on my store, when a customer orders 1 or 2 items the shipping is ok because my “default box” is big enough to ship either. But when I get an order for 5 or larger, I get hosed on shipping because I need to use a considerably larger box! I would be willing to pay for an app that has this functionality! How does Shopify not have a solution for this yet?
May I know which carrier you are using for handling the shipping process?
As you have mentioned, Shopify only allows you to set up a default box and it doesn’t work for merchants having products with different dimensions. The problem with using Shopify’s single box size is that you will be undercharging for some orders, and you will be responsible for paying out of pocket for the additional shipping cost. If you overcharge for shipping, customers will abandon their cart.
I would suggest you use the Multi Carrier Shipping Label app, that helps you handle this with ease. With the box packing method in the app, you can set up different packages for your products based on the weight & dimensions. So, whenever your customer places an order, the app automatically chooses the right box and calculates the rates accordingly. Also, with the app, you can print labels, and also automate the tracking process. You can try the app with a 14-day free trial and contact the support for any assistance required.
Have there been any updates to this issue? I’m having the exact same problem. I can’t use the calculated rates by carrier because the price will be calculated for the default box shipping one item, but if the buyer purchases 2 or more the box dimensions will change as will the shipping rates.