How to calculate a discount
- Enter the original price and the discount percentage.
- If another offer applies on top, such as a coupon or bank offer, enter it as the extra discount.
- If tax is added at the till, enter the tax rate; it's charged on the discounted price.
- Read the final price, what you save and the effective discount.
Discount formulas
- Sale price:
price × (1 − discount ÷ 100) - Two discounts:
price × (1 − d1 ÷ 100) × (1 − d2 ÷ 100) - Effective discount:
d1 + d2 − d1 × d2 ÷ 100 - With tax:
final price = sale price × (1 + tax ÷ 100)
In plain words, a second discount is taken off the already reduced price, so two discounts multiply rather than add. That's why 20% + 10% off comes to 28% off, not 30%. Money is rounded to the paisa or cent, as at a till.
Worked example
A ₹2,000 jacket with 20% off in a sale, and a 10% coupon on top:
- After 20% off: 2,000 × 0.8 = ₹1,600.
- After the extra 10% off: 1,600 × 0.9 = ₹1,440.
- You save ₹560, which is 28% of the original price.
- If 5% tax is then added: 1,440 × 1.05 = ₹1,512.
Stacked discounts at a glance
| Discounts | You pay | Effective discount |
|---|---|---|
| 10% + 10% | 81% | 19% |
| 20% + 10% | 72% | 28% |
| 25% + 10% | 67.5% | 32.5% |
| 30% + 20% | 56% | 44% |
| 50% + 10% | 45% | 55% |
| 50% + 20% | 40% | 60% |
A sign reading "up to 70% off" or "flat 50% + extra 20%" rarely means the sum. Check the effective figure before you compare offers. For other percentage sums, use thepercentage calculator.
Common uses
- Checking a sale price. Enter the tag price and the discount to see what you'll pay at the till and how much you save, before you reach the checkout.
- Stacking a coupon on a sale. Add a coupon or bank offer as the extra discount to see the real combined discount when it applies on top of a sale price.
- Pricing a promotion. Shop owners can test discount levels and see the final price, including tax, before announcing an offer.