Discount Calculator

A discount looks like simple arithmetic, yet retail pricing is full of traps — compounded percentages, "up to" wording, and prices that already include tax. This calculator cuts through it: enter the original price and the discount percentage, and it returns the amount you save and the final price, working from the familiar case of 25% off ₹2,000 to show its logic.

The formula

Final price = Original price × (1 − discount ÷ 100)
Final price = 2,000 × (1 − 25 ÷ 100) = 2,000 × 0.75 = ₹1,500

The savings output is simply the original minus the final price — ₹500.

Mental-math shortcuts

Because the formula is one multiplication, familiar fractions make quick estimates effortless:

• 10% off → pay 90%: take off every tenth digit (₹2,000 → ₹1,800)
• 25% off → pay 75%: multiply by 3, divide by 4 (₹2,000 → ₹1,500)
• 50% off → pay half (₹2,000 → ₹1,000)
• 33% off → pay two-thirds: multiply by 2, divide by 3

Build any discount from these anchor fractions and you can appraise a sale without a calculator at all.

The successive-discount trap

Two discounts applied one after another never stack arithmetically into their sum. "10% off, then an extra 20% off" looks like 30% — but:

₹2,000 × 0.90 = ₹1,800   (after the first 10%)
₹1,800 × 0.80 = ₹1,440   (after the extra 20%)
Net reduction = 28%, not 30%

Each discount shaves the already-reduced price. This calculator handles one discount per run; for stacked offers, apply it twice — a real 28%-off deal is entered as 28, not 30.

Discounts that aren't what they seem

• "Buy one get one free" on a two-for-₹2,000 item is a 50% discount, not a free gift — good, but compute it as such.
• "Flat ₹500 off" only becomes comparable once you convert it to a percentage of the listed price.
• "Up to X%" campaigns apply the peak rate to a handful of items; your item's real rate is what the tag says.
• Cash-back wording ("10% cashback") pays you later and often partially — a true discount, not an equivalent.

Convert every offer to a single common scale (final amount paid) before comparing retailers.

Tax on the discounted price

In India, GST is charged on the discounted price, not the original. On the ₹1,500 discounted item at 18% GST:

GST = ₹1,500 × 0.18 = ₹270
Final outgo = ₹1,500 + ₹270 = ₹1,770

The out-of-pocket total is larger than the sticker — build tax and delivery into real-world comparisons.

The margin cost of discounting

A discount is not free money for the seller — it comes straight out of margin. An item marked up 25% over cost (a 20% margin) that sells at 20% off returns exactly to its cost: ₹100 cost → ₹125 price → ₹100 after 20% off, no profit at all. Marked up only 10%, the same 20% discount deep-sells the item below cost. Sellers therefore cap discounts at a fraction of their markup, and "50% off" almost always signals a heavily pre-inflated list price. Reading the math this way turns a price tag into a negotiation tool.

Practical checks

• Compare final prices, not discount percentages — a smaller discount on a cheaper base frequently wins.
• Stack a coupon and a sale manually: apply the smaller percentage first, then the larger, using the running price.
• Include taxes and shipping whenever you compare two offers as rupee totals.

Common mistakes

• Adding percentages (10% + 20% = 30%) instead of multiplying the discounted fractions.
• Applying the discount to the tax-inclusive price when the store discounts the pre-tax price.
• Reading the discount percentage as the money saved — 25% off ₹2,000 saves ₹500, while 25% of ₹2,000 is a different thing entirely.

A quick cross-check on this page's default: 25% off ₹2,000 must always yield ₹1,500 final and ₹500 savings — if your own arithmetic disagrees, one of the inputs is being misread.