A discount reduces the price of an item by a certain percentage. Understanding how discounts work helps you make smarter purchasing decisions, compare deals accurately, and avoid common marketing tricks that make savings seem larger than they actually are.
The discount formula
A 30% discount on a $120 item: Savings = $120 × 0.30 = $36. Sale price = $120 − $36 = $84. Equivalently, $120 × 0.70 = $84 (you pay 70% of the original).
Common discount scenarios
- 10% off $59.99: $59.99 × 0.90 = $53.99. You save $6.00.
- 25% off $199.99: $199.99 × 0.75 = $150.00. You save $50.00.
- 40% off $85: $85 × 0.60 = $51.00. You save $34.00.
- 50% off $249: $249 × 0.50 = $124.50. You save $124.50.
How stacked discounts work
A "20% off plus an extra 10% off" sale is not the same as 30% off. Stacked discounts are applied sequentially, not added together:
- $100 with 20% off = $80. Then 10% off $80 = $72.
- $100 with 30% off = $70.
The stacked result ($72) is always less of a discount than the combined percentage ($70) because each successive discount applies to a smaller amount. The order doesn't matter mathematically — 20% then 10% gives the same result as 10% then 20%.
Don't forget about tax
In most US states, sales tax is calculated on the discounted price, not the original price. So a $100 item at 25% off with 8% tax: sale price = $75, tax = $75 × 0.08 = $6.00, total = $81.00. Use our sales tax calculator to find the final out-the-door price after both discount and tax.
Finding the original price from a sale price
If a store says "now $75 after 25% off," you can find the original price using the reverse percentage calculator. The formula: Original = Sale Price ÷ (1 − Discount% ÷ 100). So: $75 ÷ 0.75 = $100 original price.