Discount Calculator
A discount is a reduction from the original price, expressed as a percentage. Three calculation types cover most real-world scenarios: finding the final price after a percentage discount; finding what percentage discount was applied between an original and sale price; and reverse-calculating the original price from a discounted price plus the discount rate. The key formula people often get wrong is the reverse calculation: original price = discounted price ÷ (1 − discount rate). In retail, understanding how sequential discounts compound matters: a 20% discount followed by a further 10% off is not 30% off, it's 28% off the original price, because the second discount applies to the already-reduced price. Australian Consumer Law (ACL) requires that advertised 'was/now' prices reflect a genuine prior selling price, this calculator can verify whether a stated percentage matches the actual markdown.
Frequently Asked Questions
How do I calculate a discount percentage?
Multiply the original price by the discount percentage expressed as a decimal (e.g. 20% = 0.20), then subtract that amount from the original price. For example, $120 with 25% off: $120 × 0.25 = $30 saved, making the sale price $90.
What is the formula for discount?
Sale Price = Original Price − (Original Price × Discount %). This can also be written as Sale Price = Original Price × (1 − Discount %). For example, $150 with 30% off = $150 × 0.70 = $105. This formula works for any discount percentage and is the basis of how most discount calculators function.
How do I find the original price from a sale price?
Divide the sale price by (1 − discount percentage expressed as decimal). For example, $85 after a 30% discount: $85 ÷ 0.70 = $121.43 original price. This reverses the discount calculation and tells you what the item cost before the reduction, useful when comparing prices across different discount deals and assessing whether a sale is genuinely good value.
What is a "percent off" versus "percent of"?
"30% off" means you pay 70% of the original price. "30% of" means that's the amount you save. Both calculations produce the same final result because they describe the same relationship from different angles. Retailers use "percent off" phrasing because it emphasises the savings amount rather than the final price.
What is double discount and how is it calculated?
Apply the first discount to the original price, then apply the second discount to the reduced price. Two 20% discounts = 0.80 × 0.80 = 0.64 (36% total off, not 40%). The order of sequential discounts doesn't change the final result.
What is the psychological effect of showing discounts?
Showing both the original price and sale price uses anchoring and loss aversion to make the discounted price feel like a gain rather than a cost. The original price serves as a reference point that makes the current price seem better value, increasing purchase intent and perceived fairness of the deal.