Discount Calculator

Discount = Original price × Discount % ÷ 100

Final price = Original price − Discount

Discount % = (Original price − Sale price) ÷ Original price × 100

With tax charged on the discounted price:

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

A product priced at $80 with 20% off:

• You save: $16.00
• Final price: $64.00
• With 8% sales tax added: $69.12

Tax rates differ by country and region, so enter the rate that applies to your sale. The discount maths is the same in any currency.

A discount looks like a small concession on price but lands entirely on profit. On an item costing $80 and selling at $100, the $20 profit is 20% of the price: a 10% discount takes $10 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.

Most sales tax, VAT and GST systems charge tax on the price after a discount given at the time of sale, so tax falls with the discount. Discounts given after the sale are treated differently from country to country. Under India's GST, for example, they reduce the taxable value only if they were agreed before the supply and can be linked to the original invoices through a credit note.