By the Tooliday Team. Last updated 14 November 2026.
“Flat 20% off”, “extra 10% on top”, “buy one get one free”. Sales are full of percentages, and it is easy to misjudge what you will actually pay. This guide shows the simple maths behind discounts so you can compare offers with confidence. You can check every example with our Discount Calculator.
Final price after one discount
Discount amount = price × discount ÷ 100
Final price = price − discount amount
Example: a shirt costs ₹2,499 with 20% off. The discount is 2,499 × 20 ÷ 100 = ₹499.80, so you pay ₹1,999.20. A faster route is to multiply by what you pay: 80% of the price, or × 0.80.
Another: ₹1,200 with 35% off. You pay 65%, so 1,200 × 0.65 = ₹780, saving ₹420.
Two discounts do not add up
Suppose the shirt has 20% off, and a coupon gives an extra 10% on the reduced price. Many people assume that is 30% off. It is not, because the second discount is taken from ₹1,999.20, not from ₹2,499.
- After the first discount: ₹1,999.20
- Extra 10% off that: ₹199.92
- Final price: ₹1,799.28
- Total saving: ₹699.72, which is an effective discount of 28%
The shortcut is to multiply the factors: 0.80 × 0.90 = 0.72, so you pay 72% of the original price. A bigger example: 50% followed by 20% leaves 0.50 × 0.80 = 0.40, so you pay 40% and the effective discount is 60%, not 70%.
Finding the discount percentage
Sometimes you see two prices and want to know the real discount.
Discount % = (original − sale) ÷ original × 100
An item marked ₹2,499 sells for ₹1,999. The saving is ₹500, and 500 ÷ 2,499 × 100 is about 20.01%.
Finding the original price
If you only know the sale price and the discount, divide the sale price by what you paid as a fraction. ₹1,999.20 after 20% off is 1,999.20 ÷ 0.80 = ₹2,499. Do not add 20% to ₹1,999.20, which would give a wrong answer, because the 20% was taken from the larger original price.
Buy one, get one free
Buying two items and paying for one means you pay half for each, so it equals 50% off, provided you actually want both items. If you only need one, the offer saves you nothing.
Smart checks before you buy
- Compare final prices, not percentages. 30% off a higher starting price can cost more than 20% off a lower one.
- Check the starting price. A “discount” from an inflated price is not a real saving. Compare with the same item in other shops.
- Look at what is excluded. Coupons often have minimum spends, caps or exclusions.
- Add tax and delivery. Check the total at checkout. If GST applies, see How to Calculate GST.
Try it yourself
Enter a price and one or two discounts in the Discount Calculator to see the final price, your saving and the effective discount. You can also enter an original and a sale price to find the real percentage off.
This article is for general information. Prices, taxes and offer terms differ between sellers, so always check the final amount before you pay.