Discount Calculator: 20% Off vs 30% Off vs Buy 1 Get 1 Free

Not all discounts are equal. BOGO is not always 50% off. "Extra 20% on already 30% off" is not 50% off. This guide decodes every discount structure with exact math.

1.Basic percentage discount: the formula every Indian consumer needs

Discount amount = MRP × (discount% / 100). Sale price = MRP × (1 - discount%/100). Example: MRP ₹2,000, 35% off. Discount = ₹700. Sale price = ₹1,300. Always start here before comparing. For verification: ₹1,300 / ₹2,000 = 65% = 100% - 35%. If the math doesn't work, the "discount" claim may be misleading. Many Indian e-commerce listings inflate MRP artificially before applying a percentage off — always check whether the "original price" is realistic by searching the same product on other platforms.

2.Successive discounts: "30% off, then extra 20% off" is NOT 50% off

Successive discounts multiply, not add. 30% off then 20% off: first discount 30% → you pay 70% of MRP. Second discount 20% on 70% → you pay 70% × 0.80 = 56% of MRP. Total effective discount = 44%, not 50%. Formula: effective discount = 1 - (1 - d1)(1 - d2). Example: 40% + 20% off = 1 - (0.6)(0.8) = 1 - 0.48 = 52% off (not 60% off). On a ₹10,000 purchase: 52% off = ₹4,800. If you assumed 60% off = ₹4,000 and are surprised by the ₹4,800 price, this is why. E-commerce flash sales in India frequently advertise "additional X% off" — always compute the true effective rate.

3.Buy 1 Get 1 Free: the real discount percentage

BOGO (Buy 1 Get 1 Free) is 50% off only if you were going to buy 2 units anyway. If you buy 1 unit at ₹500 and get a free one, you pay ₹500 for what would have cost ₹1,000 — yes, 50% effective discount on the combined purchase. But if you only needed 1 unit and the free second unit goes to waste (or you store it for a year), the value is less — you effectively paid ₹500 for one unit, no discount. The trap: retailers know BOGO increases volume. You may buy ₹1,000 worth of goods to "save 50%" when you only needed ₹500 worth. The only time BOGO is truly 50% off: when you were already planning to buy 2 units at full price.

4.Cashback vs instant discount: which is actually better

Instant discount: ₹200 off on a ₹1,000 purchase = you pay ₹800 immediately. Value: ₹200. Cashback ₹200 credited in 7 days: you pay ₹1,000 now, get ₹200 in 7 days. Effective value: ₹200 minus the time cost. For small amounts, the difference is negligible. For large purchases (₹30,000 cashback on electronics), the 30-90 day cashback delay has real value implications. Additionally, cashback is often conditional — "cashback is applicable only if you don't return the item within 30 days." Instant discount has zero conditions. When comparing offers: instant discount > cashback of same amount, assuming both are genuine.

5.The EMI "discount": when 0% EMI is not actually free

Many Indian retailers offer "0% EMI" on credit cards for 6-12 months. This seems free, but: (1) The retailer is often charging you a processing fee of 1-3% upfront (look at the invoice carefully). (2) The retailer pays the bank a "merchant discount rate" which is recovered by inflating the MRP — the "MRP" on 0% EMI products can be 5-8% above the cash price. (3) You lose the 30-45 day float benefit of a full credit card payment. 0% EMI math: ₹60,000 product on 6-month 0% EMI with 2% processing fee = ₹60,000 + ₹1,200 = ₹61,200. Compare to paying cash/debit: often ₹56,000-58,000 for the same product. The "free" EMI costs ₹3,200-5,200.