How the Discount Calculator works

Enter the original price and the discount percentage, and the calculator shows the sale price and how much you save. The discount amount is the price multiplied by the percentage divided by 100, and the sale price is the original price minus that amount. If a second, extra discount applies, it is taken off the already reduced price. If your region adds sales tax at the till, enter the tax rate and the calculator adds it to the sale price to give the final amount you actually pay.

A worked example

Say a jacket costs 80 and is 25% off. The discount is 80 × 0.25 = 20, so the sale price is 80 − 20 = 60. Now add 8% sales tax: 60 × 0.08 = 4.80, so the final price is 64.80. The percentage is always applied to the price it refers to, so the order matters when there is more than one step.

Why two discounts are not simply added together

A common surprise is that 30% off followed by an extra 10% off is not 40% off. The second discount is taken from the lower price, not the original one. On an item that costs 120, 30% off brings it to 84, and a further 10% off 84 brings it to 75.60. You saved 44.40 in total, which is 37% of the original price, not 40%. The more steps a sale has, the more the real discount falls short of the numbers added together, so it is worth checking with the calculator.

Working backwards from the sale price

Sometimes you know the sale price and the discount and want the original price. Divide the sale price by one minus the discount as a decimal. If something is 25% off and now costs 45, the original price was 45 ÷ 0.75 = 60. This is a useful check when a shop shows only the reduced price, and it is a quick way to see whether the “was” price is realistic.

Quick mental math

You can estimate many discounts in your head. For 10% off, move the decimal point one place to the left and subtract, so 10% off 60 saves 6. For 20% off, double that saving. For 25% off, take a quarter, and for 50% off, halve the price. Combine these steps for other rates, for example 15% is 10% plus half of 10%. The calculator is there when you want an exact figure with cents, tax, or more than one discount.

Tips for comparing deals

A bigger percentage is not always the better deal. A 30% discount on an expensive item can still cost more than a 10% discount on a cheaper one, so compare the final prices rather than the percentages. Check whether tax and delivery are included, whether a coupon can be combined with a sale, and whether the discount applies to the full basket or only to selected items. This tool gives general information only, and the price you pay is set by the seller.