How to Calculate Discounts and Final Sale Prices

Discount calculations are among the most common everyday math problems. Whether you are at a sale, comparing coupons, or checking whether a "deal" is actually saving you money, knowing the formulas lets you verify the math in seconds.

Three types of discount problems

You will encounter three variants: (1) Final price = Original × (1 − discount rate). For a $80 item at 25% off: 80 × 0.75 = $60. (2) Discount amount = Original × discount rate: $80 × 0.25 = $20 off. (3) Discount rate = (Original − Sale) / Original × 100: if $80 drops to $60, the rate is 25%.

Stacked discounts

If a store applies two discounts sequentially — say 20% off then an additional 10% off — you do not add them. Instead, multiply: 0.80 × 0.90 = 0.72, meaning you pay 72% of the original price, which is a 28% total discount. This is why "20% + 10% off" is not the same as "30% off."

Using the discount calculator

Enter the original price and the discount percentage. The calculator shows your savings amount and the final price instantly. You can also work backwards — enter the sale price and original price to find the discount percentage that was applied, which is useful for verifying advertised deals.