In-depth
How to Calculate Percentage Discounts: Formulas and Practical Examples
The percentage discount is one of the most commonly used mathematical operations in everyday life. From seasonal sales to online promotions, knowing how to calculate the discounted price — or work backward from the discounted price to the original — is an essential skill for making informed purchases.
The basic discount formula
The formula for calculating the discounted price is:
Discounted price = Original price × (1 − Discount% ÷ 100)
Or, in two steps:
- Calculate the discount amount: Discount = Original price × Discount% ÷ 100
- Subtract: Final price = Original price − Discount
Practical discount calculation examples
| Original price | Discount | Amount saved | Final price |
|---|---|---|---|
| €100.00 | 10% | €10.00 | €90.00 |
| €79.90 | 25% | €19.98 | €59.93 |
| €249.00 | 30% | €74.70 | €174.30 |
| €49.99 | 50% | €25.00 | €25.00 |
| €1,200.00 | 15% | €180.00 | €1,020.00 |
How to calculate the discount percentage
If you know the original price and the discounted price, you can determine the discount percentage applied:
Discount% = (Original price − Discounted price) ÷ Original price × 100
Example: a product was €80 and now costs €60. The discount is: (80 − 60) ÷ 80 × 100 = 25%.
How to find the original price
If you only know the discounted price and the discount percentage, you can calculate the starting price:
Original price = Discounted price ÷ (1 − Discount% ÷ 100)
Example: an item costs €63 after a 30% discount. The original price was: 63 ÷ (1 − 0.30) = 63 ÷ 0.70 = €90.
Watch out for "discount on discount"
During sales, some stores apply an additional discount on an already discounted price. This mechanism is often misunderstood: two 30% discounts do not equal a 60% discount.
Here's how it works:
- Original price: €100
- First discount 30%: 100 × 0.70 = €70
- Second discount 30% (on the already reduced price): 70 × 0.70 = €49
The actual total discount is 51%, not 60%. The general formula for compound discounts is:
Total discount% = 1 − (1 − D1 ÷ 100) × (1 − D2 ÷ 100) × 100
Most common discount-on-discount table
| 1st discount | 2nd discount | Actual total discount |
|---|---|---|
| 20% | 10% | 28% |
| 30% | 20% | 44% |
| 40% | 20% | 52% |
| 50% | 30% | 65% |
| 30% | 30% | 51% |
Tips for sales shopping
- Compare the original price: verify that the full price shown was actually charged before the sale.
- Always calculate the final price: don't be fooled by high percentages — what matters is the actual price you pay.
- Factor in shipping costs: for online purchases, shipping can negate the discount advantage.
- Compare across stores: the same product with a 20% discount in one store might cost less at full price in another.
How to use the calculator
Enter the original price and the discount percentage, then press "Calculate" to instantly get the final price and the amount saved. You can also use the reverse function to find out what discount percentage was applied or to determine the original price.
