How to Track Custom Option Performance in Shopify GA4

To track custom product option performance in Shopify with Google Analytics 4 (GA4), you need to implement enhanced eCommerce tracking combined with custom events or parameters that capture the specific options selected by customers. Here’s how to set it up:

1. Install GA4 Properly on Shopify

If you haven’t already:

  • Use Google Tag Manager (GTM) to install GA4.
  • Optionally use Stape.io or another server-side tagging platform for more accurate data collection, especially post-iOS 14.

2. Capture Custom Option Data Using Data Layer

You’ll need to push the selected product options into the dataLayer when a user adds a product to cart or completes a purchase.


window.dataLayer = window.dataLayer || [];
window.dataLayer.push({
  event: "add_to_cart",
  ecommerce: {
    items: [{
      item_name: "Custom Mug",
      item_id: "custom-mug-123",
      price: 19.99,
      quantity: 1,
      item_category: "Mugs",
      item_variant: "Red",
      custom_option_text: "Happy Birthday John",
      custom_option_font: "Script",
      custom_option_addon: "Gift Box"
    }]
  }
});

You can extract these values using Shopify’s line_item.properties in the cart or checkout pages.

3. Map Data Layer to GA4 via GTM

  1. Create GTM Variables for each custom parameter (e.g., custom_option_font).
  2. Edit your GA4 event tags (like add_to_cart or purchase) and pass the variables as parameters.

Example GA4 Event Tag in GTM:


event: "add_to_cart",
parameters: {
  item_name: {{Item Name}},
  item_id: {{Item ID}},
  custom_option_font: {{DL - Font}},
  custom_option_text: {{DL - Text}},
  custom_option_addon: {{DL - Addon}}
}

4. Register Custom Dimensions in GA4

To view these parameters in GA4 reports:

  • Go to Admin → Custom Definitions → Create Custom Dimension
  • Scope: Event
  • Parameter name: Must exactly match the one in your GTM (e.g., custom_option_font)

5. View & Analyze in GA4

Use Explore → Free Form in GA4 to build reports that show:

  • Top-selling custom options
  • Conversion rates per option
  • Revenue generated from specific customizations

Bonus: Shopify Line Item Properties

If you’re using an app like SM Product Options, the customization data is stored in line_item.properties.

You can inject those properties into the dataLayer on the cart or thank-you page using Shopify Liquid and pass them into GTM.

Recommended Tools

  • Shopify + GTM
  • GA4 property setup
  • Custom Options app (e.g., SM Product Options)
  • GTM Debug Mode + GA4 DebugView
  • Optional: Stape.io for server-side tagging

Need Help?

If you want help creating the GTM container, Liquid code, or debugging your setup, feel free to reach out. We can provide:

  • GTM dataLayer snippets
  • GA4 custom reports
  • App-specific tracking examples

💡 Tip: You can also use this method to pass data to Facebook CAPI, TikTok, or Pinterest pixels for enhanced retargeting based on product options.

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