Discount Calculator
Figure out sale prices, discount percentages, or original prices. Handles stacked discounts like "20% off, then an extra 10% off" and optional sales tax on the final price.
For stacked offers like "20% off, then an extra 10% off the sale price." Note: 20% + 10% stacked is not 30% — it's 28%.
Tax is applied to the sale price (after discount), matching most US jurisdictions.
How the Discount Calculator Works — and Why “Extra 20% Off” Isn't What It Sounds Like
Discounts look straightforward. A jacket marked “30% off” should cost 30% less than its original price, right? Usually, yes — but the moment stores start stacking discounts, adding coupons, or applying them in a particular order, the math becomes something most shoppers get wrong. Stores know this, and some of them count on it. Understanding how discounts actually compound will make you a savvier buyer, and it'll help you spot the difference between a genuine deal and marketing sleight of hand.
The basic formula
A single discount is easy: sale price = original price × (1 − discount ÷ 100). A $120 jacket at 30% off costs 120 × 0.70 = $84. If you want to work backward — say you know the sale price and original price but want the discount percentage — the formula is discount % = ((original − sale) ÷ original) × 100. Both calculations take only a second, but they're the foundation for every other discount situation, including the tricky ones.
Why stacked discounts don't add up
This is where most shoppers get fooled. If a store offers “20% off, then an extra 10% off,” you might assume that's the same as 30% off. It isn't. The first discount reduces the price, and the second discount applies to the already-reduced price — not the original. On a $100 item: 20% off brings it to $80, then 10% off that brings it to $72. The effective discount is 28%, not 30%. The general rule: two consecutive discounts of a% and b% produce a total discount of (a + b − (a × b ÷ 100)), which is always less than a + b. The same logic applies to coupons, clearance sales on already-discounted items, and store loyalty programs that layer on top of everything else.
Sales tax and the order of operations
Sales tax is calculated on the final price after all discounts are applied, not the original price. This is important because it's the opposite of what some people assume. If a $100 item is 20% off and your local sales tax is 8%, you pay 80 × 1.08 = $86.40, not (100 × 1.08) − 20 = $88. That $1.60 difference might not matter much on one purchase, but it adds up over a year of shopping, and the same principle applies to restaurants, hotels, and any purchase where tax is added at checkout. The calculator lets you enter a tax rate to see the true out-the-door price.
Limitations and things to watch for
Discounts are often genuine, but retailers use several tactics to make sales look bigger than they are. Some brands inflate the “original” price before a sale, so the discount appears larger than the real markdown. Others advertise a percentage off while raising the base price across the board. Watch for “up to X% off” phrasing — that means only a few items reach the maximum, and most are discounted far less. Also note that some discounts can't be combined with others, and some exclude sale items or specific brands, even if the fine print isn't visible until checkout. Finally, this calculator doesn't account for rewards points, cash-back offers, or credit card bonuses, which can effectively reduce the price further. Use it to see the true math behind a sale, then decide whether the deal actually saves you money or just feels like it does.