How to Calculate a Discount

Calculate the saving, then the price

For an original price of 80 and a 15% discount, the saving is 80 × 15 ÷ 100 = 12. Subtract 12 from 80 to obtain a sale price of 68. Equivalently, multiply 80 by the retained fraction 0.85. The first method highlights the saving; the second goes directly to the remaining price. Both describe the same transaction before other charges.

The discount calculator displays the reduction and final price from a single percentage discount. Read the rate field as a percentage: enter 15 for fifteen percent, not 0.15. A quick check is that a 15% reduction should be smaller than a 20% reduction, which would remove 16 from a price of 80. This estimate catches misplaced decimals before you compare offers.

Work out the discount from two prices

If a product falls from 150 to 117, the saving is 33. Divide that saving by the original 150 and multiply by 100: the discount is 22%. Dividing by 117 would measure the saving relative to the sale price, not the reduction from the original. The percentage change reference explains why choosing the denominator changes the meaning of the percentage.

When comparing shops, check that the products are equivalent. A 30% reduction on a higher starting price can still leave a higher checkout price than a 20% reduction elsewhere. Compare the same model, quantity, condition and delivery terms. The percentage helps describe the offer, but the payable amount is usually the relevant number when deciding between identical purchases.

Stacked percentages multiply

Two successive discounts of 20% and 10% do not combine into 30%. Starting at 100, the first leaves 80 and the second removes 8, leaving 72. The combined reduction is 28%. In one expression, multiply 100 × 0.8 × 0.9. For any series of percentage discounts, multiply the retained fractions to find what remains.

With exact arithmetic, reversing those two percentage discounts gives the same result because multiplication is commutative. However, an actual checkout may round at intermediate steps or apply eligibility conditions, so read the offer terms. Use the calculator for one step at a time and preserve the displayed amounts if you are reconciling a receipt. Our percentage basics guide explains the reverse-price formula as well.

Fixed coupons behave differently

A fixed coupon and a percentage discount can depend on order. On a price of 100, taking 20% off and then subtracting a 10 coupon gives 70. Subtracting the coupon first leaves 90, and then taking 20% off leaves 72. Neither sequence is universally correct: the retailer's terms determine which operation applies first and which items qualify.

Minimum-spend rules introduce another boundary. A coupon requiring an eligible basket of 100 might use the amount before discounts or after them. Do not assume delivery, taxes or excluded products count toward that threshold. A mathematical comparison should state its assumptions explicitly instead of presenting one sequence as a rule for every shop. This article explains the arithmetic, not a jurisdiction's consumer or tax law.

Recover an original price

If an item costs 84 after a 30% reduction, the final price represents 70% of the original. Divide 84 by 0.7 to recover 120. Adding 30% to 84 gives 109.20 and does not undo the reduction, because the increase uses a smaller base. This is the same asymmetry explored in percentage increase calculations.

A 100% discount is a special case: a zero final price does not identify the original price. Many different original amounts could be reduced to zero. The reverse formula would divide by zero, so it cannot recover a unique answer. For ordinary positive prices and discounts below 100%, substituting the recovered original price back into the forward calculation provides a simple verification.

Compare baskets instead of advertising claims

Suppose one shop sells an item for 72 plus 8 delivery, while another charges 78 with delivery included. The second checkout total is lower even if the first advertises the larger discount. If a multi-buy offer changes the quantity, compare price per unit and whether you need every unit. Spending more to obtain a lower unit price is not automatically a saving on the purchase you intended.

Keep money calculations at full precision until the final step unless you are reproducing a stated checkout rounding policy. For a receipt dispute, retain the original price, discount terms and line-item amounts rather than relying on a rounded percentage alone. How to calculate a percentage provides the basic part-and-whole method behind these examples and helps distinguish a numerical saving from a genuinely cheaper overall purchase.

Compare a fixed saving with a percentage offer

Suppose you can choose either 15 off an eligible purchase or a 20% discount, but cannot combine them. The offers are equal when 20% of the eligible price is 15. Solving 0.2P = 15 gives P = 75. Below 75, the fixed saving is larger under these assumptions; above 75, the percentage saving is larger. At a price of 100, the percentage removes 20 rather than 15.

That crossing point assumes both offers cover the same amount and neither has a cap, minimum spend or exclusion. If the percentage saving is capped at 12, it never exceeds the 15 fixed saving where both are usable. If the fixed coupon requires a minimum basket of 80, it is not an available alternative at a price of 60. Eligibility must be checked before comparing numerical savings.

You can use this method to organize a real offer comparison without turning the calculator into a checkout simulator. Write the eligible price, each offer's formula and any restrictions. Calculate the final payable amount for each valid option, then add the same relevant charges. This makes the reasoning auditable and prevents an attractive percentage from distracting from a condition that removes or limits the saving altogether.