Formula
Sale price = price × (1 − d) × (1 − e)Total discount = 1 − (1 − d)(1 − e) How it works
A discount is a percentage taken off the original price. To find the sale price, multiply the price by what is left after the discount: 25% off means you pay 75%, so a $80 item costs $80 × 0.75 = $60.
Stacked discounts multiply rather than add. "30% off, then an extra 20% off" leaves you paying 70% × 80% = 56% of the original price — a 44% discount, not 50%. The calculator applies the extra discount to the already-reduced price, which is how stores almost always do it.
Sales tax is normally charged on the price after discounts, so the "price with tax" line applies your tax rate to the final sale price.
Frequently asked questions
How do I calculate a discount in my head?
Find 10% by moving the decimal one place left, then scale. For 30% off $45: 10% is $4.50, so 30% is $13.50 and the sale price is $31.50.
Does the order of stacked discounts matter?
No. Because the discounts multiply, 20% then 30% off gives exactly the same price as 30% then 20% off.
How do I find the original price from a sale price?
Divide the sale price by the fraction you paid. A $60 item that was 25% off originally cost $60 ÷ 0.75 = $80.