First, divide the discounted price by the original price. Type the original prices and sales prices into a worksheet as shown as below screenshot: 2. 1. Formula to find out the discount value. 1. 2. =0.15. Note: you're still paying $60 of the original $80. 3. Calculate Percentage Discount. Subtract this result from 1. This equals 75%. Note: the result is a decimal value, and must be formatted using the Percentage number format in Excel to display as a percentage. Select a blank cell, for instance, the Cell C2, type this formula = (B2-A2)/ABS (A2) (the Cell A2 indicates the original price, B2 stands the sales ... 3. For example, if you would like to know the discounted value of something that costs €3,000 and has a discount of 15%: Calculate discount rate with formula in Excel. There are several ways of discovering a discount percentage for any value but the most simple is: discounted value = (discount percentage * total value) / 100. In the example, the active cell contains this formula: =1- (D5/C5) In this case, Excel first divides the discounted price in D5 (59.5) by the original price in C5 (70) to get 0.85, which is then subtracted from 1: =1- (59.5/70) =1-0.85. Note: if you're still paying 75%, you're not paying 25% (the percentage discount).