The core formula is straightforward: Sale Price = Original Price × (1 - Discount Rate). For example, an item priced at $100 with 25% off costs $100 × 0.75 = $75.
If you know the sale price and discount rate, you can reverse-calculate the original price: Original Price = Sale Price ÷ (1 - Discount Rate).
The most common scenario. A store sign says "25% off" — you pay 75% of the original price. Enter the original price and discount percentage, and the calculator gives you the sale price and savings instantly.
"Take 20% off, then an extra $10" — you can't just add percentages. The correct way: apply the percentage first, then subtract the fixed amount. Many e-commerce platforms use this trick; the calculator helps you verify the real savings.
A friend says "I got this for $60, it was 40% off" — what was the original price? Use reverse mode: $60 ÷ 0.60 = $100. Handy for secondhand shopping and price comparisons.
10% off → pay 90%
20% off → pay 80%
25% off → pay 75%
50% off → pay 50% (half price)
75% off → pay 25% (quarter price)