Working out a sale price is one short formula — but the sneaky bits (stacked offers, whether tax comes before or after the discount) trip people up at the till. This guide covers the basics and the traps, with a free discount calculator for the moment you're standing in the shop.
The discount formula
Discount = original price × (percent off ÷ 100)
Sale price = original price − discount
Or in one step: sale price = original × (1 − percent ÷ 100).
Worked example
A ₹2,500 jacket at 30% off:
| Discount | 2,500 × 0.30 = ₹750 |
| Sale price | 2,500 − 750 = ₹1,750 |
Or straight to the answer: 2,500 × 0.70 = ₹1,750.
Quick mental tricks
- 50% off — just halve it.
- 10% off — move the decimal one place (₹2,500 → ₹250 off).
- 20% off — take 10% twice, or double 10%.
- 25% off — quarter it: divide by 4 to get the discount.
- 15% off — 10% plus half of that 10%.
Stacked discounts don't simply add
“30% off, then an extra 20% off” is not 50% off. The second discount applies to the already-reduced price: ₹2,500 → 30% off = ₹1,750 → 20% off that = ₹1,400. That's a real saving of 44%, not 50%. Discounts multiply, they don't add.
Finding the percent off
Spotted a price drop and want the percentage? Use percent off = (original − sale) ÷ original × 100. A ₹2,500 item now ₹1,750: (2,500 − 1,750) ÷ 2,500 × 100 = 30%. This is the same percentage-change maths covered in the percentage calculator. If GST is added after the discount, apply it to the sale price using the GST calculator.
FAQ
How do I find the sale price? Multiply the original by (1 − percent/100). For 30% off, multiply by 0.70.
Do stacked discounts add up? No — the second applies to the reduced price, so 30% then 20% is 44% off, not 50%.
Is tax before or after the discount? Usually the discount comes first, then tax on the reduced price — but check your receipt.
Is my data private? Yes — the calculator runs in your browser and stores nothing.