Discount Calculator

When this calculator helps

Percentages off look easy until you are doing the arithmetic at the register or scanning a flood of Black Friday and Cyber Monday deals. This calculator tells you, fast, the sale price you will pay and the dollars you are saving from any percentage-off promotion — clearance markdowns, store coupons, promo codes, loyalty rewards, and employee or student discounts all work the same way through it.

It is just as useful for comparison shopping as it is at checkout. When one retailer advertises '40% off $75' and another simply posts 'now $50,' converting both to a single dollar figure tells you which is genuinely cheaper. And because US promotions love to stack coupons on top of sale prices, it pays to know how to chain reductions correctly so a stack that looks like it adds up to half off turns out to be what it actually is.

How to read your result

The calculator returns two figures: the sale price you pay and the amount you save. Check the saving against the headline to make sure the math lines up — a true 25% off $80 should show $20 saved and a $60 sale price. If the saving comes out smaller than expected, the discount is probably being figured on a lower base than you thought.

The trap to avoid is stacking. Two discounts never add up. A 30% reduction followed by an extra 20% coupon is not 50% off — the second cut applies to the already-reduced $56, not the original $80, so you land at $44.80, a real saving of 44%. Successive percentages multiply instead of summing, which is why a chain of big-sounding coupons saves less than adding the numbers suggests. Run each reduction through the calculator in order to see the true running subtotal.

A worked example

Say a pair of running shoes is marked at $150 with a '30% off' sale, and you have a $20-off-equivalent store coupon worth an extra 15% on sale items. Apply the 30% first: $150 becomes $105, a $45 saving. Now apply the 15% to that $105, not to the original $150 — that takes off $15.75, leaving $89.25 before tax. Your pre-tax saving is $60.75, which is about 40.5% off the original, not the 45% you would get by adding 30 and 15. Then sales tax is applied to the $89.25, so the lower discounted price also shrinks the tax you owe.

Common mistakes to avoid

Most discount errors come from how the percentages combine and where tax enters the picture.

• Adding stacked percentages together — '30% then 20%' is 44% off, not 50%, because the second coupon applies to the reduced price.
• Confusing '% off' with '% of' — 25% off means you pay 75% of the price, not 25% of it.
• Forgetting that the price tag excludes sales tax, so the discounted figure here is a pre-tax subtotal, not the final amount at the register.
• Comparing two offers by their headline percentages instead of the actual dollar price you would pay.

US sales tax notes

The key difference in the US is that the price on the shelf almost always excludes sales tax — tax is added at the register, and the rate varies by state, county, and city. So the discounted figure this calculator gives you is the pre-tax subtotal, not the final out-the-door total. To get what you actually pay, take the sale price here and then apply your local combined sales tax rate on top.

The good news for shoppers is that sales tax is generally charged on the discounted price, not the original. A store coupon or percentage-off promotion lowers the taxable amount, so a deeper discount also trims the tax you owe — the saving compounds slightly in your favor. (Manufacturer rebates that mail money back later often do not reduce the taxable price, and a few states treat certain coupon types differently, so check your state's department of revenue if you need certainty.)