Discount Calculator
Enter the original price and one percentage discount. The calculator shows the final price and how much you save, rounded to the cent, and the two always add up to the original price. For a second discount on top, such as an extra 15% off at checkout, press Add another discount. With two or more, it also shows the combined discount and what each one takes off.
How to use the Discount Calculator
- Enter your numbers in the Discount Calculator above.
- Press the Calculate button to see the result.
- To try other numbers, change any value and press the button again.
The discount formula
Final = Original × (1 − d) · · · Savings = Original − Final · · · Two discounts: Final = Original × (1 − d1) × (1 − d2)
The calculator rounds the final price half up to the cent. Stacked discounts multiply. They don't add, so 20% off and then 10% off is (1 − 0.20)(1 − 0.10) = 0.72 of the price, which is 28% off in total, not 30%. With several discounts it works from the original price each time, so the order makes no difference to the final price.
Worked example
A $150 item at 25% off: the calculator shows a final price of $112.50 and a saving of $37.50. Add a second discount of 15% for an extra 15% off at checkout. The final price is $95.63, because 112.50 × 0.85 = 95.625 rounds up to the next cent, and you save $54.37. Against the original $150 that is 36.25% off, not the 40% you would get by adding the two percentages.
Frequently asked questions
Why don't discounts simply add?
Because the second discount applies to the already-discounted price, not the original. The savings on the second pass are smaller in dollar terms. On $150, 25% takes off $37.50 and the 15% after it takes off $16.87.
Does a store have to stack discounts this way?
No, a store sets its own rules, and some coupons cannot be combined or apply only to full-price items. The calculator works out the price if each percentage applies on top of the last one. Read the terms of the offer to see whether that happens at checkout.
Why is my result a cent away from doing it by hand?
Rounding after each step can move the answer by a cent, because the next step starts from a rounded price. $10.05 at 50% and then 50% is $2.51 here, because 10.05 × 0.25 = 2.5125 rounds once. Rounding after the first step gives $5.03, and half of that rounds up to $2.52.
How do I find the original price from a sale price?
The calculator doesn't work backwards, so do it by hand. Divide the sale price by (1 − discount). A $60 item at 25% off had an original price of 60 / 0.75 = $80. Enter $80 at 25% and the calculator shows $60.00 to check it.
Are coupons applied before or after sale prices?
It depends on the retailer, so read the coupon terms. For two percentage discounts the order doesn't matter, because the multiplication gives the same final price either way. A flat-dollar coupon is different. On a $100 item, $10 off and then 20% off leaves $72, while 20% off and then $10 off leaves $70. The calculator handles percentage discounts only.