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.