How to Calculate a Discount
Discount calculations are among the most practical everyday math skills. Whether you're evaluating a sale, applying a coupon, or comparing prices at competing retailers, understanding discount math helps you make better purchasing decisions and spot misleading marketing.
The Four Discount Calculations
This calculator handles all discount scenarios: (1) Find the sale price when you know the original price and discount percentage. (2) Find the sale price when you know the original price and a fixed dollar discount. (3) Find what percentage discount you received when you know the original and sale price. (4) Find the original price when you know the sale price and discount percentage — useful for reverse-engineering "was" pricing.
Percentage Discount Formula
Final Price = Original Price × (1 − Discount Rate). A 30% discount on $200: $200 × (1 − 0.30) = $200 × 0.70 = $140. Savings = $200 − $140 = $60. Equivalently: Savings = $200 × 0.30 = $60. The second approach (multiply by the discount rate) is faster for finding only the savings amount.
Stacked Discounts
When multiple discounts apply, they don't simply add up. A 20% discount followed by an additional 10% off the sale price is not 30% off the original — it's 28% off. Calculate each step sequentially: $100 × 0.80 = $80, then $80 × 0.90 = $72. The combined effective discount is 28%, not 30%.
Evaluating "Sale" Pricing
Always compare the final price to actual market prices rather than the stated "was" price. Retailers sometimes inflate "original" prices to make discounts appear larger than they are. A 50% off label means nothing if the "original" price was never actually charged. Use price history tools and comparison shopping to verify genuine savings.