Add to Cart Isn't Working? Here's How to Troubleshoot

If your calculator is displaying correctly but the Add to Cart button isn't working as expected, one of the following issues is usually the cause.

1. Extra Shopify Variants

The default (variant-based) flow creates a hidden Shopify variant for the calculated price. If your product already has many variants, this can lead to conflicts.

How to fix it:
Switch your calculator to the Non-Variant Flow (Cart Transform) in the calculator settings. This method doesn't require additional Shopify variants.

2. Cart Drawer Theme Conflict

Some Shopify themes use a cart drawer that slides in from the side. In certain themes, the item is added successfully, but the drawer doesn't open or the page reloads unexpectedly.

How to fix it:
In your Shopify admin, go to:
Online Store → Themes → Customize → Theme Settings → Cart
Change the cart type from Drawer to Page, then test the calculator again.

3. Incorrect Add to Cart Selector

Custom Price Calculator needs to know which button on your product page is the Add to Cart button. If the selector doesn't match your theme, clicking the button may do nothing.

How to fix it:
Open your calculator and go to:
Settings → Add to Cart Selector
Verify that the selector matches your theme's Add to Cart button.

4. Calculated Price Is $0

If your formula returns a price of $0, Shopify may reject the Add to Cart request.

How to fix it:
Review your pricing formula and confirm that:

• All required inputs are connected correctly.
• The formula calculates a value greater than zero before adding the product to the cart.

5. Slow Response in Non-Variant Flow

When using the Non-Variant Flow, the app relies on Shopify's Cart Transform API. Occasionally, Shopify may take a few seconds to process the request, making the Add to Cart button appear unresponsive.

How to fix it:
Wait a few seconds and try again. If the delay happens consistently, please contact our support team so we can investigate.

Still Need Help?

If the issue persists, please send us:

• Your product page URL.
• A description of what happens when you click Add to Cart (nothing happens, page reloads, error message, etc.).
• Any browser console errors (open your browser's developer tools and check the Console tab).

With this information, we'll be able to troubleshoot the issue much more quickly.

Updated on: 26/07/2026