Apply a discount to an ecommerce event

Page Summary

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• Discounts can be applied to items in an ecommerce event by using the discount parameter.

• Do not use percentage discounts with the discount parameter; instead, provide the value of the discount.

• You can report on item-level discounts using the "Item coupon", "Order coupon", and "Item revenue" dimensions and metrics.

• To report on event-level discounts, you will need to create a custom metric.

You can apply a discount to an item in an ecommerce event by adding the discount parameter with the value of the discount. Don't use a percentage for the discount parameter.

gtag.js Tag Manager

Example

A customer applies a discount code ("SAVE20") to an order containing three units of one item (originally $10.00 each) and one unit of another item (originally $22.00 each). The discount is allocated as $2 per unit for the first item and $4.40 per unit for the second.

Summary of the example calculation

Before sending the event, you must calculate the discounted price for each item. Google Analytics does not automatically subtract the discount value from the price.

• value = Sum of item revenues = $24.00 + $17.60 = $41.60

Here's the purchase event tag for this example:

// A user applies the coupon code "SAVE20" to their entire order.
// The order contains three units of one item type, and one unit of another item type.
gtag("event", "purchase", {
  'transaction_id': "T_12345",
  'value': 41.60,        // Total value after all discounts
  'currency': "USD",
  'coupon': "SAVE20",    // Order-level coupon code
  'items': [
    {
      'item_id': "SKU_123",
      'item_name': "Blue Widget",
      'price': 8.00,       // Unit price after discount (original 10.00 - 2.00 discount)
      'discount': 2.00,    // Unit discount
      'quantity': 3,
      'coupon': "SAVE20"   // Optional: Item-level coupon can match order-level
    },
    {
      'item_id': "SKU_456",
      'item_name': "Red Widget",
      'price': 17.60,      // Unit price after discount (original 22.00 - 4.40 discount)
      'discount': 4.40,    // Unit discount
      'quantity': 1,
      'coupon': "SAVE20"
    }
  ]
});

Report on the discount

The following dimensions and metrics allow you to report on discount:

Handle event-level and item-level discounts

A coupon can be added to the entire order (event-level) or to a specific product (item-level).

• Order-level: To apply a coupon to the entire transaction, add the coupon parameter at the event level (outside the items array).
• Item-level: To apply a coupon to a specific item, add the coupon parameter within that specific object in the items array.

If a coupon applies a discount to the entire order (event-level), you should allocate that discount across the items in the event to ensure accurate item-level reporting.

In each item object:

1. Add the discount parameter with the allocated unit discount value for the item.
2. Set the price to the unit price minus the allocated unit discount for the item.

You can also create a custom metric to report on event-level discounts.