To find a sale price, multiply the original price by 1 minus the discount as a decimal. With 25% off a price of 80 you pay 80 × 0.75 = 60 and save 20. Two discounts in a row multiply: 25% and then 10% off is 32.5% off in total, not 35%.
Formulas
sale price = price × (1 − % ÷ 100)% off = (was − now) ÷ was × 100 Examples
- Shoes at 120 with 35% off: 120 × 0.65 = 78, so you save 42.
- Was 50, now 40: (50 − 40) ÷ 50 × 100 = 20% off.
Common mistakes
- Adding stacked discounts. 20% and then 10% off is 28% off in total, because the second discount applies to the reduced price.
- Finding the original price with the wrong base. If 60 is the price after 25% off, the original is 60 ÷ 0.75 = 80, not 60 × 1.25 = 75.
In Excel and Google Sheets
- Price in A2, discount % in B2
=A2*(1-B2) - % off from old price A2 to new price B2
=(A2-B2)/A2
FAQ
How do I calculate 30% off?
Multiply the price by 0.7. For 30% off 90: 90 × 0.7 = 63, and you save 27.
Is 50% off and then another 50% off free?
No. The second 50% applies to half the price, so you pay a quarter of the original: 75% off in total.
Should tax go before or after the discount?
Usually after: discount first, then tax on the reduced price. Both are multiplications, so the final price comes out the same either way.
How we calculate: exact decimal math (no rounding errors), you choose the decimal places, and your numbers never leave your browser. Methodology →
Updated October 2026