What is the Discount?
Stacked discounts do not add up. "40% off plus an extra 10%" is not 50% off — the second discount applies to the already-reduced price, giving an effective 46%. This is the most common piece of sale mathematics that shoppers get wrong.
Formula & worked example
Effective discount = 1 − (1 − d₁) × (1 − d₂)
Worked example: ₹4,999 with 40% off = ₹2,999.40. A further 10% off brings it to ₹2,699.46. You save ₹2,299.54, an effective discount of 46% — not the 50% the signage implies.
How to use this discount calculator
- Enter the original price or MRP.
- Enter the first discount percentage.
- Add a second discount if one stacks (coupon, card offer, extra sale).
- Add GST only if it is charged on top rather than included in MRP.
Smart tips
- Two stacked discounts always total less than their sum. 40% + 10% is 46%, not 50%.
- In India MRP is usually GST-inclusive. Only add GST if the seller lists a pre-tax price.
- Check whether the "original price" is a genuine former selling price — inflated MRPs are the oldest trick in retail.
- Compute price per unit or per use before buying in bulk. A bigger discount on something you will not finish is not a saving.
Frequently asked questions
Is 40% plus 10% off the same as 50% off?
No. The second discount applies to the reduced price, so the effective discount is 46%. A flat 50% is always better.
How do I calculate a discount percentage?
Divide the saving by the original price and multiply by 100. Saving ₹2,300 on ₹4,999 is a 46% discount.
Is GST charged on the discounted price?
Yes, GST applies to the actual transaction value after discount. In India MRP is normally GST-inclusive already.
How do I know if a sale price is genuine?
Compare against the price history on other retailers. Artificially high "original" prices are a common way to make modest discounts look large.
Want the theory behind the numbers? Read our shopping guides on the Money Blog.
Written by Gurjeet Singh, Sharpen Solutions. Last reviewed 30 Sep 2026. How we check these numbers.