To calculate the discount percentage, you need to know the original price and the discounted price. The formula to calculate the discount percentage is: Discount Percentage = [(Original Price - Discounted Price) / Original Price] x 100 Here's an example: Suppose you want to calculate the discount percentage for a product that originally cost $100 but is now being sold for $80. Discount Percentage = [(100 - 80) / 100] x 100 Discount Percentage = [20 / 100] x 100 Discount Percentage = 20% Therefore, the discount percentage for the product is 20%.