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How to set up the GA4 ecommerce dataLayer

Live guide · Checked 28 October 2026 · Updated 28 October 2026 · Checked every week against Google Analytics 4's own help pages

Push view_item, add_to_cart, begin_checkout and purchase in the format GA4 expects, and send them with one tag, so revenue, products and checkout drop-off all show in GA4.

Time
45 minutes
You will need
  • Google Tag Manager and the Google tag for GA4
  • A developer or a platform plugin that can add code to product, basket, checkout and order pages
Stuck?
Troubleshooting or ask us a question

Step by step

  1. Use GA4's item format

    Every ecommerce event carries an items list in the same shape. Use the same item_id your shop uses:

    JavaScript
    {
  item_id: 'SKU-1042',
  item_name: 'Oak desk',
  item_brand: 'Northwood',
  item_category: 'Desks',
  price: 249.00,
  quantity: 1
}

  2. Clear the old ecommerce data first

    Before every ecommerce push, clear the last one, or items from one event leak into the next:

    JavaScript
    window.dataLayer = window.dataLayer || [];
window.dataLayer.push({ ecommerce: null });

  3. Product page: view_item

    JavaScript
    window.dataLayer.push({ ecommerce: null });
window.dataLayer.push({
  event: 'view_item',
  ecommerce: { currency: 'GBP', value: 249.00, items: [{ item_id: 'SKU-1042', item_name: 'Oak desk', price: 249.00, quantity: 1 }] }
});

  4. Basket and checkout: add_to_cart and begin_checkout

    Push add_to_cart when something is added (with the items added), and begin_checkout when checkout opens (with everything in the basket):

    JavaScript
    window.dataLayer.push({ ecommerce: null });
window.dataLayer.push({
  event: 'begin_checkout',
  ecommerce: { currency: 'GBP', value: 298.00, items: [
    { item_id: 'SKU-1042', item_name: 'Oak desk', price: 249.00, quantity: 1 },
    { item_id: 'SKU-2210', item_name: 'Desk lamp', price: 49.00, quantity: 1 }
  ] }
});

  5. Order confirmation: purchase

    On the order confirmation page, once per order. The transaction_id stops repeats being counted twice:

    JavaScript
    window.dataLayer.push({ ecommerce: null });
window.dataLayer.push({
  event: 'purchase',
  ecommerce: {
    transaction_id: 'ORDER-50231',
    value: 298.00,          // after discounts, before shipping and tax is fine, just be consistent
    tax: 49.67,
    shipping: 0,
    currency: 'GBP',
    coupon: 'SPRING10',
    items: [{ item_id: 'SKU-1042', item_name: 'Oak desk', price: 249.00, quantity: 1 }, { item_id: 'SKU-2210', item_name: 'Desk lamp', price: 49.00, quantity: 1 }]
  }
});

  6. One trigger for every ecommerce event

    In Tag Manager: Triggers > New > Custom Event, tick Use regex matching, and set the event name to:

    Text
    ^(view_item|view_item_list|select_item|add_to_cart|remove_from_cart|view_cart|begin_checkout|add_shipping_info|add_payment_info|purchase|refund)$

  7. One GA4 tag for all of them

    Tags > New > GA4 Event. Set Event Name to {{Event}}, open More Settings > Ecommerce and tick Send Ecommerce data with Data source Data Layer. Fire it on the trigger above.

  8. Test and publish

    In Preview, go from a product to a test order. Check each event in Tag Assistant, then in GA4 DebugView. Publish, and give Reports > Monetisation a day to fill.

Tips from people who set these up every week

  • Using Shopify? The Shopify Customer Events Secret Setup does this for you.
  • Keep value consistent: always before or always after tax and shipping, or your ROAS will swing.

Troubleshooting: questions and answers

Revenue in GA4 is higher than my shop.

Usually purchase fires again when people reload the confirmation page. Make sure transaction_id is the real order number: GA4 removes repeats with the same id.

Items are missing in reports.

Check every item has item_id or item_name, and that Send Ecommerce data is ticked on the tag.

Official help pages

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