Discount Calculator
Free discount and sale price calculator — find the final price and the amount saved on any percentage-off deal. Type the original price and the percent off. Works in your browser.
Type in the original price and the percentage off. The calculator returns the sale price (what you’ll actually pay) and the amount saved.
The formula
saved = original × discount% ÷ 100
sale price = original − saved
Or, equivalently:
sale price = original × (100 − discount%) ÷ 100
A 30% discount means you pay 70% of the original. Always.
Stacking discounts
A “30% off then an extra 20% off” deal is not 50% off. The 20% is taken off the already discounted price:
0.70 × 0.80 = 0.56
So the final price is 56% of the original — a 44% discount overall. Stacked percentage discounts always come out less than the sum of the percentages.
Tax
Sales tax (in jurisdictions that have it) is computed on the sale price,
not the original. So a discount also saves you on tax. To get the all-in
out-the-door price, multiply the sale price by 1 + tax_rate.
Reverse the calculation
If you see a $84 item marked “30% off” and want to know the original:
original = sale price ÷ (1 − discount ÷ 100) = 84 ÷ 0.70 = $120
Useful sanity check on suspiciously round “savings” claims.
Worked examples
-
30% off a $120 item
Sale price: $84.00 — you save $36.00.
-
15% off a $60 item
Sale price: $51.00 — you save $9.00.
Frequently asked questions
What's the formula for a percentage discount?
Multiply the original price by the discount as a fraction of 100, and subtract. Saved = original × discount ÷ 100; sale price = original − saved. Equivalently, sale price = original × (100 − discount) ÷ 100.
How do I quickly do this in my head?
Move the decimal point left once to get 10%, double it for 20%, halve it for 5%, and combine. 30% off $120 → 10% is $12, so 30% is $36 saved, $84 to pay. With practice it's faster than typing.
How do I stack two discounts?
Apply them one after the other, not by adding. 30% off then 20% off is **not** 50% off — it's `0.7 × 0.8 = 0.56` of the original, i.e. 44% off. Stacked discounts always come out less than the sum.
What about sales tax?
Sales tax is computed on the sale price (the price after discount), not the original. So you save tax on the discounted amount too. This calculator returns the pre-tax sale price; multiply by `1 + tax rate` to get the out-the-door figure.
How do reverse-discount calculations work?
If you know the sale price and the discount, the original is `sale ÷ (1 − discount/100)`. So a $84 sale price at 30% off implies an original of `84 ÷ 0.7 = $120`. We may add a reverse / sale-to-original mode in a future version.