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How to Use the Discount Calculator
- Enter the original price before the discount.
- Enter the advertised percentage off.
- Leave sales tax at 0% for the sale price alone, or enter the applicable tax rate.
- Review the final price, amount saved, discounted price before tax, and tax amount.
How Discount Calculations Work
Discount amount equals original price multiplied by the discount percentage divided by 100. Subtract that amount from the original price to get the price before tax. When a tax rate is entered, the calculator applies it to the discounted price rather than the original price.
In formula form: savings = original price x discount rate / 100. Price before tax = original price - savings. Final price = price before tax x (1 + tax rate / 100).
Discount Calculator Examples
25% off an $80 item
The savings are $20 because $80 x 0.25 = $20. The sale price before tax is $60.
30% off $149.99 with 8.25% sales tax
The discount saves about $45.00, leaving $104.99 before tax. Tax adds about $8.66, so the displayed final price is $113.65 after rounding each displayed result to cents.
100% off a $50 item
A 100% discount removes the full $50 price. The discounted price and tax amount are both $0.
Why Two Discounts Do Not Simply Add Together
Successive discounts apply one after another. For example, 20% off followed by another 10% off does not equal 30% off. A $100 item becomes $80 after the first discount and $72 after the second, for an effective discount of 28%. Use the calculator for one advertised discount at a time unless a store explicitly combines them into one rate.
Common Discount Calculation Mistakes
A frequent mistake is subtracting the percentage number as dollars, such as treating 20% off $50 as $30 instead of $40. Another is applying sales tax to the original price when the local checkout applies tax after eligible discounts. Receipt rules, fees, coupons, rebates, and tax treatment can vary, so use the store receipt for the final charged amount.