Shopping maths made simple

Discount Calculator: How to Calculate Sale Prices and Savings

A discount calculator helps you work out how much a product's price is reduced during a sale. Enter the original price and the discount percentage to find the amount you save and the price you would pay before any extra charges. You can also use a discount calculation to estimate an original price, work out a percentage reduction, understand successive discounts, or compare two offers.

The calculator above supports several commonly used currencies for display. It does not exchange one currency for another, and the result is an estimate when taxes, delivery charges, coupons, or retailer-specific rules are involved.

1. How to use the discount calculator

1. Choose the calculation mode that matches the information you know.
2. Enter the original price, sale price, discount rate, or other requested values.
3. Select the currency in which you want the amounts displayed.
4. Choose Calculate discount to view the answer and calculation breakdown.
5. Use Reset to restore the starting values, or copy/share the result when your browser supports the feature.

2. Discount amount formula

The discount amount is the money removed from the original price. Convert the percentage to a decimal by dividing it by 100, then multiply it by the original price.

Example: A backpack is priced at 80 currency units and has a 15% discount. The discount amount is 80 × 15 ÷ 100 = 12 currency units. The symbol depends on the currency you are using.

3. Final sale price formula

Subtract the discount amount from the original price to find the reduced price before any additional taxes or fees.

For the backpack above, the sale price is 80 − 12 = 68 currency units. A useful alternative is to multiply the original price by the percentage that remains. At 15% off, 85% of the price remains, so 80 × 0.85 = 68.

4. Worked discount examples

These examples use generic price units so the arithmetic is the same for USD, EUR, INR, GBP, BRL, or another currency. The values are not currency conversions.

5. How successive discounts work

Some shops advertise an offer such as “20% off, then an extra 10% off.” The second discount is normally calculated on the price remaining after the first discount, not on the original price.

For an item costing 1,000 units, a 20% discount reduces the price to 800. A further 10% discount takes 80 off that new price, giving a final price of 720. The total savings are 280 units, or 28% of the original price. Adding 20% and 10% to claim 30% off would be incorrect for successive discounts of this kind.

6. Find an original price from the sale price

If you know the final sale price and the percentage discount, you can reverse the calculation to estimate the original price. This works for discounts below 100%.

For example, if a product costs 75 units after a 25% discount, then 75 ÷ 0.75 = 100 units was the implied original price. A 100% discount cannot be reversed this way because the denominator becomes zero and the original price cannot be uniquely determined from a free final price alone.

7. Find the discount percentage from two prices

When you know both prices, subtract the sale price from the original price to find the savings. Then divide the savings by the original price and multiply by 100.

If a product falls from 120 units to 90 units, the savings are 30 units. The discount percentage is 30 ÷ 120 × 100 = 25%.

8. Compare shopping offers fairly

A larger advertised percentage does not always mean a better deal. A product originally priced at 100 units with 20% off costs 80 units. Another product priced at 90 units with 15% off costs 76.50 units. The second offer has the smaller percentage discount but the lower final price.

When comparing offers, check that you are comparing like-for-like products and include relevant delivery charges, taxes, membership fees, minimum-spend requirements, and coupon conditions. Product quality, warranty coverage, and return policies can matter too.

9. Optional sales tax: what to know

Tax treatment varies between countries, regions, and retailers. In a common tax-exclusive example, the discount is applied to the taxable price first and tax is then calculated on the reduced amount. If the price already includes tax, the tax portion must be separated from the tax-inclusive total instead of added again.

The optional tax feature is an estimate, not a universal tax-law calculator. Your checkout total can differ because of local rules, item-specific tax rates, shipping, rounding, and other discounts. Check the seller's displayed total for the amount you will actually pay.

10. Common discount calculation mistakes

• Adding successive discounts: A 20% discount followed by 10% off is generally 28% overall, not 30%.
• Comparing only the percentages: Compare final prices and the full terms of each offer.
• Forgetting extra charges: Taxes and shipping may affect the checkout total.
• Mixing currencies: Changing the calculator's currency changes formatting only; it does not convert the amount at an exchange rate.
• Reversing a 100% discount: The original price cannot be derived uniquely from a zero price and a 100% discount alone.
• Rounding too early: Keep intermediate calculations precise and round currency amounts for display or according to the applicable payment rules.

Frequently asked questions

Disclaimer: This tool provides general arithmetic estimates for shopping decisions. It is not a guarantee of a retailer's checkout price, tax liability, or promotion eligibility. Always review the merchant's terms and the final price before purchasing.