Discount Calculator

Up to 70 percent off, and what the up to is doing

Sale banners in India run on two words that carry no promise: “up to”. Big Billion Days on Flipkart, the Great Indian Festival on Amazon, the Myntra end-of-season sale, all of them advertise “up to 70% off” and “up to 80% off”, and each of those means that one item, somewhere in the category, carries that discount. Usually an odd size, a last-year colour or a model the brand has stopped making. The item you actually want is at 30 or 40.

The calculator does not care about the banner. It takes the four things printed on the listing and gives you the price you will pay:

• MRP or listed price, the figure the discount is quoted against.
• Discount, the tag percentage.
• Extra discount, the bank-card or coupon offer. “10% instant discount with SBI credit cards” belongs here. It is applied on the price after the tag discount, not added to the tag discount, and the calculator does it that way because the marketplace does.
• GST. Leave it at 0 for anything with an MRP or a marketplace price, because those already include tax. Use it only for a quote written ex-GST.

A ₹2,999 pair of shoes, 40 percent off, plus a 10 percent card offer

Those are the defaults, and they are a fairly ordinary festival-sale listing.

after tag discount  = 2,999 x 0.60 = 1,799.40
after card offer    = 1,799.40 x 0.90 = 1,619.46

Listed price	₹2,999.00
You pay	₹1,619.46
You save	₹1,379.54
Real discount	46.00%
Price before GST	₹1,619.46
GST	₹0.00

The listing will show “40% off” and a green line underneath saying “10% off with SBI cards”, and the mind adds them to 50. A true 50 percent discount would have been ₹1,499.50. The stacked offer is worth 46 percent, and the ₹119.96 between the two is the bank offer being calculated on ₹1,799.40 rather than on ₹2,999.

The gap grows with the size of the percentages. On a ₹10,000 item:

Offer as printed	Reads as	Real discount	You pay
10% + 10%	20%	19%	₹8,100
30% + 20%	50%	44%	₹5,600
25% + 25%	50%	43.75%	₹5,625
50% + 50%	100%	75%	₹2,500

Two 50 percent discounts cannot make anything free. Order does not matter for two percentages (30 then 20 is the same as 20 then 30), but it matters a great deal once a flat rupee coupon enters, which is the next section.

Card offers also carry a cap that the calculator cannot see. “10% instant discount, up to ₹1,500, on orders above ₹5,000” is 10 percent on a ₹12,000 order and only 7.5 percent on a ₹20,000 phone, because ₹1,500 is what you get either way. When the cap binds, divide the cap by the price and enter that as the extra discount. And note that the cap is on the discounted price at most marketplaces, not on the MRP, so on a large purchase the bank offer is worth a smaller percentage than the banner says twice over.

Flat ₹500 off or 10 percent off: which one wins depends on the price

Coupons come in both forms and the checkout page usually lets you apply only one. The crossover is the flat amount divided by the percentage:

crossover = 500 / 0.10 = ₹5,000

Below ₹5,000, the flat ₹500 is worth more. Above it, the 10 percent is. On the ₹2,999 shoes, 10 percent is ₹299.90 and the flat coupon is ₹500, so the coupon wins by ₹200. On an ₹8,000 pair of headphones, 10 percent is ₹800 and the coupon loses.

The flat coupon usually has a minimum cart value written in small type, and it is often set just above the crossover, which is not an accident. “Flat ₹500 off on orders above ₹4,999” is a coupon designed to be worth slightly less than 10 percent to anyone who can use it.

Where order matters: a flat ₹500 taken off before a 10 percent bank discount and after it differ by ₹50, because the bank discount is 10 percent of whatever remains. Marketplaces apply the coupon first and the bank offer last, in your favour. A shop that does it the other way round is keeping the ₹50, and it is worth checking the bill.

MRP is not the market price, so a discount on MRP proves nothing

Every packaged product in India carries a maximum retail price, and under the Legal Metrology rules a seller may not charge more than it. Nothing stops a seller charging less, and for clothing, footwear, cosmetics and small electronics the everyday selling price sits well under the MRP all year.

That is the whole trick of a percentage-off tag. A shirt with an MRP of ₹2,999 that has sold at ₹1,499 since it arrived in the shop is “50% off” on the tag every day of the year. During the sale it goes to ₹1,299 and the tag says “57% off”, and the actual saving against what anyone was paying is ₹200, about 13 percent.

Things I would do before believing a discount:

1. Check what the same listing sold at last month. Price-history browser extensions do this for Amazon and Flipkart, and the number is often higher in the week before the sale than the week after.
2. Compare the final price, including delivery, across two or three sellers. The percentage is a description of one seller’s MRP, not of the market.
3. Ignore the strike-through price entirely when the same brand’s own website is cheaper. It frequently is, for footwear especially.

The Central Consumer Protection Authority’s 2023 guidelines on dark patterns name false urgency and drip pricing as unfair practices, and “only 2 left” banners next to a “was ₹2,999” price are exactly the pattern they describe. Enforcement is patchy. The calculator’s “real discount” line, measured against the price you would otherwise have paid rather than the MRP, is the protection that works today.

GST sits on the discounted price, not the MRP

For anything with an MRP, GST is already inside the number and the box should stay at 0. Where the box matters is a quote written before tax: a laptop bag ordered in bulk for an office, a service invoice, a car accessory from a dealer. There, GST is charged on the price after the discount, as long as the discount is shown on the invoice at the time of sale; the CGST Act lets a discount recorded on the invoice be deducted from the taxable value.

A ₹25,000 quote with 10 percent off and 18 percent GST:

	Correct	GST on the pre-discount price
Price before GST	₹22,500.00	₹22,500.00
GST	₹4,050.00	₹4,500.00
You pay	₹26,550.00	₹27,000.00

The second column is what a shop gets when the billing software applies the discount as a line item after tax rather than before it. The ₹450 is not a rounding error; it is 18 percent of the discount, and on a corporate order it is worth asking the seller to reissue the invoice. The GST calculator will pull the tax back out of an inclusive total if you need to check a bill in the other direction.

Once the price is settled, two other pages take over. If the purchase is going on a no-cost EMI, which is never quite no-cost, the EMI calculator shows what the instalments really add up to, and for a bigger ticket the personal loan calculator does the same with processing fees. For plain percentage arithmetic, a hike or marks or a rate change, the percentage calculator answers all three forms from the same two numbers.