Dynamic Pricing for Custom Products without an App

Technical Q&A
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Topic summary

Goal: Build an interactive “weigh and pay” product page where customers select up to 7 ingredients from 50+ options and enter quantities in 0.01 increments; store combines and ships the order.

Key constraints encountered:

  • Shipping weight: Shopify doesn’t allow overriding/passing dynamic shipping weights to the cart. Current workaround is using product variants representing shipping weights (1–11 kg) and selecting the correct variant based on total order weight to get accurate rates. Asking if there’s a better native method.
  • Dynamic pricing: Cannot pass a computed total price for the custom-composed item to cart/checkout. Aware of apps that create temporary products with custom price/weight, but wants to avoid them due to UI glitches and site issues.
  • Seeking clarity: Is there a native solution (without apps) for both dynamic shipping weight and pricing? Open to documentation or implementation pointers.

Status: Unresolved; soliciting developer guidance. No code or attachments provided.

Summarized with AI on December 15. AI used: gpt-5.
1

Hi friends,

I’m wondering if anybody can provide any guidance for me. I’m looking to create an interactive Product page that allows customers to create their own weigh and pay style product online. I’ll essentially be dynamically pulling data into a dropdown option box which allows the user to select a product from a list of 50+ options. Once selected the customer can enter a quantity into an input field for that product with steps = 0.01. Then they can reiterate through the process up to 7 times for different ingredients. We then weigh and combine these products and ship them off.

Ive already started playing around with it a little bit and I think ive come across shopify limitations:

  1. You cant override and pass through shipping weights to the cart.

To solve this I’ve created variants for shipping weights from 1-11kg which is generally the maximum we’d expect people to order. We then calculate the total weight of the customers total order and pass through the variant with the correct shipping weight to the cart so our shipping costs can be calculated accurately. Is there another way to do this?

  1. I cant figure out how to pass through the total price for the custom cart item through to the cart for checkout.

I’ve seen apps that seem to get around this by creating new products with a new shipping weight and price but id really rather not do this. Is there a way around it?

  1. Am I missing something and there’s just a solution for both that Im not aware of?

I know there’s apps that can basically do what im asking but the UI for the customer is really glitchy in all the apps ive tried, the two apps that worked unfortunately added bugs to other areas of our website that they couldn’t fix and led to store conversion issues.

Any dev wizards out there id really appreciate some input, or even just point me in the direction to do some reading and learn more

Cheers!!