Discount Calculator
Calculate percent off and stacked discounts
Quick Facts
- •20% + 10% stacked = 28% total (not 30%)
- •Half price = 50% off
- •Buy-one-get-one = 50% off when buying 2
How Discounts Work
A percentage discount reduces the original price by that percentage. For a 25% discount on a $100 item: $100 × 0.25 = $25 off, final price = $75. Stacked discounts apply sequentially — a 20% off + 10% off is NOT 30% off but rather 28% total.
Understanding the discount calculator
The trap in discounts is stacking. Two 20 percent discounts are not 40 percent off, because the second applies to a price that has already fallen. Retailers know this, which is why 'extra 20 percent off sale prices' reads bigger than it works out to. Reversing the arithmetic also matters: knowing what a sale price implies about the original tells you whether a deal is real.
Worked examples
Two stacked discounts of 30 and 20 percent on 200
- 1First discount: 200 × (1 - 0.30) = 140.
- 2Second discount applies to 140: 140 × (1 - 0.20) = 112.
- 3Total saved: 200 - 112 = 88.
- 4Effective single discount: 88 ÷ 200 = 44 percent, not 50.
A final price of 112, an effective 44 percent off.
Working out the original price from a 63 sale price at 30 percent off
- 1The sale price represents 70 percent of the original.
- 2Divide: 63 ÷ 0.70 = 90.
- 3Check: 90 × 0.30 = 27, and 90 - 27 = 63.
The original price was 90 and the saving is 27.
Effective discount when two offers stack
| First | Second 10% | Second 20% | Second 30% | Second 50% |
|---|---|---|---|---|
| 10% | 19.0% | 28.0% | 37.0% | 55.0% |
| 20% | 28.0% | 36.0% | 44.0% | 60.0% |
| 30% | 37.0% | 44.0% | 51.0% | 65.0% |
| 40% | 46.0% | 52.0% | 58.0% | 70.0% |
| 50% | 55.0% | 60.0% | 65.0% | 75.0% |
Quick percent off reference
| Original | 10% off | 25% off | 40% off | 60% off | 75% off |
|---|---|---|---|---|---|
| 20 | 18.00 | 15.00 | 12.00 | 8.00 | 5.00 |
| 50 | 45.00 | 37.50 | 30.00 | 20.00 | 12.50 |
| 100 | 90.00 | 75.00 | 60.00 | 40.00 | 25.00 |
| 250 | 225.00 | 187.50 | 150.00 | 100.00 | 62.50 |
| 500 | 450.00 | 375.00 | 300.00 | 200.00 | 125.00 |
Frequently asked questions
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This calculator is for educational and reference purposes only. Always verify critical calculations independently.