Discount percentage calculator
Multiply the price by the discount as a decimal and you get the money off. Multiply by what is left instead and you get the price you actually pay, in one step. The calculator above does either.
12 × 12 = 144
Adding 12 to itself 12 times gives the same answer.
Two multiplications, and one of them is better
- Money off = price × discount ÷ 100. Thirty percent off 80: 80 × 0.30 = 24.
- Price you pay = price × what is left. 80 × 0.70 = 56.
Use the second one. It is a single multiplication with no subtraction afterwards, which is where the mistakes usually creep in.
The multiplier to enter
| Discount | Multiply price by | Discount | Multiply price by |
|---|---|---|---|
| 10% | 0.90 | 40% | 0.60 |
| 15% | 0.85 | 50% | 0.50 |
| 20% | 0.80 | 60% | 0.40 |
| 25% | 0.75 | 70% | 0.30 |
| 30% | 0.70 | 75% | 0.25 |
Going the other way, from two prices
Discount percent = (old price − new price) ÷ old price × 100. Was 80, now 56: 24 ÷ 80 = 0.3, so 30% off. Divide by the old price. Dividing by the new one gives 42.9%, which flatters the deal by a wide margin, and it is the single most common error on this calculation.
Stacked discounts do not add
Twenty percent off, then a further ten percent at the till, is not thirty percent off. Multiply the two multipliers: 0.80 × 0.90 = 0.72, which is 28% off. The same rule applies to a discount followed by a tax being added back on, so always run the multipliers in the order the shop applies them.
For the reverse of this sum see the pay raise percentage calculator, or average several percentages with the percentage average calculator. Everything else is on the calculators page.