20% Off Calculator
How a 20% discount works, the final price for common amounts, and the stacking mistake people make most often.
How to calculate it
Discount = price × 20 ÷ 100
Final = price × 80 ÷ 100 = price × 0.8Multiplying by the remaining share is faster than subtracting. For 20% off, multiply the price by 0.8 and that is what you pay.
20% off by price
| Original | Discount | You pay |
|---|---|---|
| 5,000 | 1,000 | 4,000 |
| 10,000 | 2,000 | 8,000 |
| 15,000 | 3,000 | 12,000 |
| 20,000 | 4,000 | 16,000 |
| 30,000 | 6,000 | 24,000 |
| 50,000 | 10,000 | 40,000 |
| 100,000 | 20,000 | 80,000 |
| 200,000 | 40,000 | 160,000 |
| 500,000 | 100,000 | 400,000 |
| 1,000,000 | 200,000 | 800,000 |
Working backwards to the original price
Original = discounted ÷ 0.8If a 20%-off price is 80,000, the original was 80,000 ÷ 0.8 = 100,000. Adding 20% back is not the same operation as dividing by 0.8.
Stacked discounts do not add up
Taking 20% off and then a further 10% is not 30% off. The second discount applies to the already-reduced amount: 0.8 × 0.9 = 0.72, an effective discount of 28%.
More percentage math
The full calculator also covers percentage change and VAT in one place.
Open Percent CalculatorFrequently asked questions
How do I calculate 20% off?
Multiply the price by 0.8 for the final amount, or by 0.2 for the discount itself.
What is 20% off 100,000?
80,000. The discount amount is 20,000.
How do stacked discounts work?
They multiply rather than add. 20% followed by 10% gives an effective 28%.
All calculations on this page run in your browser. Your input is never sent to a server.