Which shipping apps calculate rates by size and weight on Basic Plan?

Shopify Apps
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Topic summary

A merchant on Shopify’s Basic Plan is seeking shipping apps that calculate rates based on both product size and weight, not just weight alone. The current setup fails to recognize USPS flat-rate boxes, leading to inaccurate shipping costs and lost sales.

Key Issue:

  • Shopify Shipping on the Basic Plan only considers weight and distance, ignoring product dimensions
  • Flat-rate box options aren’t being utilized despite being configured in shipping packages
  • Carrier-calculated shipping typically requires upgrading to higher-tier plans (~$4,800/year)

Proposed Solutions:

  • Using custom shipping profiles with automation apps like Shipr (acknowledged as unlikely to solve the core problem)
  • Adding carrier-calculated shipping for $20/month to the Basic Plan (conflicting information provided)

Current Status:
The discussion remains unresolved with contradictory information. One contributor claims Shopify support confirmed carrier-calculated rates can be added for $20/month, while another reports being told a full plan upgrade is required. The original poster expresses frustration that this basic functionality isn’t included by default, especially compared to older e-commerce platforms they previously used.

Summarized with AI on October 31. AI used: claude-sonnet-4-5-20250929.
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Many thanks @krystlerae - I appreciate the help.

I had that set - the “Use carrier or app to calculate rates” for USPS - so it picks up the “Discounted rates from Shopify Shipping” automatically and adds up the weight of the order to pack the box and charges accordingly.

I need it to calculate the SIZE of the products in order to get a realistic rate for the customer, unfortunately.

For example, it’s not seeing the USPS flat rate boxes where we can save the customers postage costs for most orders. They are listed in the Shipping Packages but they are not even being considered in the calculation. If it took the size of the products into consideration, it would see that it could use these flat-rate boxes from USPS.

So is there an app for that? One that works with the Basic Plan and considers the sizes of the products in its calculation?

Am I missing something?

(This isn’t new technology and this is not a stretch to implement. I come from the GoDaddy Quick Shopping Cart that I had since 2006 (!) - their shipping calculator would pack the box accurately AND it would tell me HOW it packed it, meaning which box had what items in it. I just assumed this updated, newer Shopify program would have something similar! )