Discount Calculator
Work out the price after a discount, the percent off between two prices, stacked discounts and whether paying cash or in installments is cheaper.
Related calculators: Percentage & Rule of Three · Annual vs Monthly Interest · Loan Calculator
Frequently asked questions about discounts
Why do 20% and 10% off not add up to 30%?
The second discount applies to the price that is already reduced. 100 minus 20% is 80, and 80 minus 10% is 72, so the total discount is 28%.
Is "interest-free installments" really free?
Only when the cash price is the same as the total in installments. When the store gives a discount for paying cash, the installment plan hides an interest rate, which the calculator shows.
Which monthly rate should I type?
Type what your money would earn in the meantime, after tax: for example the monthly yield of your savings account or of a deposit you can withdraw. Type 0 if the money would sit idle.
When is Black Friday 2026?
Black Friday 2026 is on Friday, 27 November 2026, the day after Thanksgiving in the United States. Compare the sale price with the usual price before buying.
How the discount calculator works
This page has four calculations in one form. It finds the price after a discount, the percent off between an original and a sale price, the combined effect of up to five discounts applied one after another, and whether paying cash with a discount or in installments costs less. It is made for shoppers checking Black Friday 2026 deals on Friday 27 November 2026, and for buyers in Brazil comparing "à vista com desconto" with "parcelado". You can pick any of the 15 currencies, and the amounts are shown with that currency's symbol and decimals.
The final price is the original price times (1 - d/100). The percent off between two prices is (original - sale) / original x 100. Stacked discounts multiply their factors, (1 - d1)(1 - d2)..., so they never add up. For cash versus installments, each installment is divided by (1 + i)^k, where i is the monthly rate your money earns and k is the number of months from purchase (0 for an installment paid at purchase). The option with the lower value today is the cheaper one. The hidden rate is the rate that makes the installments worth exactly the cash price, found by bisection.
Example: 100 with 20% and then 10% off costs 72.00, a total discount of 28.00%, not 30%. Now take a purchase of 1,200 in 10 installments of 120 starting after one month, or 1,080 in cash (10% off). If your money earns 1% a month, the installments are worth 1,136.56 today, so paying cash saves 56.56, and the hidden rate of the plan is 1.96% a month, 26.27% a year. The results ignore taxes, fees, cashback and card points, so treat them as an estimate.