# How magento split the discount amount on each ordered item in case of shopping cart rule having fixed amount of discount on whole cart

I'm struggling to figure out how magento do that,split the discount amount on each ordered item in case of shopping cart rule having fixed amount of discount on whole cart

For example In the cart I have 3 items and there is coupon code "test5" after applied this coupon will get the discount of \$5.00. In admin on order details page magento distribute discount amount.

So I want to know the logic how magento distribute the discount amount on each ordered item. Thanks in advance!

• I noticed something else, the tax seems incorrect when summed. – Smith Oct 31 '18 at 14:53

## 2 Answers

To calculate the discount amount for each item, Magento uses the following equation: This is done in the app\code\core\Mage\SalesRule\Model\Validator.php file, process() method.

In your case: SUM of all the products ordered: \$ 161.91

Discount total: \$ 4.86

Calculates the items:

(ORIGINAL PRICE / 161.91) * 4.86 = x

1. (3.47 / 161.91) * 4.86 = \$ 0.10
2. (1.87 / 161.91) * 4.86 = \$ 0.06
3. (156.57 / 161.91) * 4.86 = \$ 4.70 Why? No such answer in Magento. But it does distribute the discount equally using the "original price" field.

Thanks Vinícius Perotto for your reply. Your answer is correct But I have also found the formula for split the discount amount on each ordered item in case of shopping cart rule having fixed amount of discount on whole cart, after review the file "app\code\core\Mage\SalesRule\Model\Validator.php", in process() method.

I thought should share with all So the formula is below that.

\$discountRate = Item price X Qty / SUM of all the items ordered

\$finalDiscountAmt = Discount total X \$discountRate

For example : (3.47 X 1) / 161.91 = 0.021

4.86 X 0.021 = \$0.10