Discount Calculator

The two calculations, with the default example

The widget does exactly two operations. First it multiplies the price by the percentage and divides by 100 to get the saving. Then it subtracts the saving from the price to get what you pay. With the defaults of 80 and 25%, the saving is 80 × 25 ÷ 100 = 20 and the final price is 80 − 20 = 60.

Decimal percentages are accepted, so a 12.5% loyalty discount on a 1,250 purchase shows a saving of 156.25 and a final price of 1,093.75. A price of 129.99 at 30% off produces a raw saving of 38.997, which is displayed as 39.00, and a final price of 90.99.

Each result is rounded to two decimal places on its own, which can produce a one-cent oddity on awkward prices. Enter 10.01 at 50% and both figures show as 5.00, because 5.005 sits just below the rounding boundary in floating-point arithmetic. For ordinary shop prices this never matters, but it is why the two numbers may not add back to the original to the cent.

Preset buttons on a typical price

Stacked offers: run the tool twice

The calculator applies a single percentage. When a store advertises 20% off plus an extra 10% at the till, the second discount is taken from the already reduced price, not from the original. Work it out in two passes: 100 at 20% off gives 80, then enter 80 as the new original price at 10% off, which gives 72. The combined reduction is 28%, not 30%.

The same two-pass approach handles a percentage coupon applied after a fixed amount off. Subtract the fixed amount yourself, then enter what is left as the original price.

Inputs the tool accepts and rejects

• The price must be greater than zero. With an empty or zero price the result panel simply stays hidden until you type a value.
• The discount field is held to the range 0 to 100 as you type: enter 120 and it snaps to 100, which leaves a final price of 0.00, and a negative percentage is reset to 0. The final price can therefore never go below zero.
• A discount of 0% is valid and shows a saving of 0.00 with the final price equal to the original, which is a quick way to confirm you typed the price correctly.
• Tax is not part of the calculation. If the discount applies before sales tax, take the final price shown here across to the Sales Tax Calculator.

Everyday situations it fits

• Checking a sale label in a shop: type the price and the advertised percentage and compare the final price with what the till charges.
• Pricing stock for a clearance: enter the retail price and try the presets until the final price lands where you want it.
• Splitting the saving on a group order: the You save figure is the total reduction, so divide it by the number of people.
• Comparing a percentage discount with a fixed amount off: find the percentage version here and see which leaves the lower final price.