Discount Calculator

Percentage discount:

Discount = Original price × Discount % ÷ 100

Final price = Original price − Discount

Flat discount:

Discount % = Discount amount ÷ Original price × 100

With GST on the discounted value:

Payable = Final price + (Final price × GST rate ÷ 100)

A product priced at ₹1,499 with 20% off:

• You save: ₹299.80
• Final price: ₹1,199.20
• With 18% GST added: ₹1,415.06

A discount looks like a small concession on price but lands entirely on profit. On an item costing ₹800 and selling at ₹1,000, the ₹200 profit is 20% of the price — a 10% discount takes ₹100 away, which is half the profit, not a tenth of it. The smaller your margin, the more violent this effect: at a 15% margin, a 10% discount removes two-thirds of the profit on every unit sold.

That maths sets the break-even volume for a scheme. To earn the same total profit after a 10% discount on a 20% margin line, you must sell twice as many units. If the scheme cannot plausibly double the volume, it is a loss dressed as marketing, and a bundled offer or a free add-on with a low cost usually protects profit better than a straight price cut.

For GST purposes, a discount shown on the invoice reduces the taxable value, so tax is charged on the net figure. Discounts given after the sale reduce taxable value only if they were agreed before the supply and can be linked to the original invoices through a credit note.