Discount Calculator
This discount calculator tells you what you'll actually pay when something goes on sale. Enter the original price and the percent off, and you'll instantly see the sale price, the dollar amount you save, and the true percentage off the original. It's the quick math check you want while standing in the aisle or hovering over a checkout button.
It also handles the two situations that trip people up: stacked discounts and sales tax. Add an extra percent off — like a "25% off, plus an additional 10% at checkout" promotion — and the calculator applies the discounts sequentially, the way stores do, so you see the real combined discount instead of the too-good-to-be-true sum. Add your local sales tax rate and you'll see the final out-the-door price too.
How it works
The calculator starts with your original price and applies the first discount to get an intermediate price. If you entered an extra discount, it applies that percentage to the already discounted price — not the original — because that's how stores stack promotions. The result is your sale price. It then reports your total savings in dollars and as an effective percentage of the original price. If you entered a sales tax rate, tax is calculated on the discounted sale price (the standard practice in most US states) and added to produce the final price.
Formula
Sale price after one discount: sale = price × (1 − d₁), where d₁ is the discount as a decimal. With a stacked second discount: sale = price × (1 − d₁) × (1 − d₂) — the discounts multiply, they don't add. Your savings are price − sale, and the effective discount is (price − sale) ÷ price × 100. With tax: final = sale × (1 + t), where t is the tax rate as a decimal.
Worked example
A jacket costs $80 and is marked 25% off. The sale price is 80 × 0.75 = $60, so you save $20 (25%). Now suppose there's an extra 10% off coupon at checkout. The 10% comes off the $60 sale price, not the $80 original: 60 × 0.90 = $54. You save $26 total — an effective 32.5% off, not the 35% you'd get by adding the two discounts together.
Prices and promotions vary by store, and the final price is set at checkout. Use this calculator as an estimate.
Frequently asked questions
How do I quickly figure out a discount in my head?
Use the 10% trick: move the decimal point one place left to get 10% of the price, then scale from there. For a $80 item, 10% is $8, so 20% off is $16 off ($64) and 25% off is $16 plus half of $8, or $20 off ($60). For 5%, take half of the 10% figure. Most common discounts are multiples of 5, so this gets you an exact answer in a few seconds.
Why don't stacked discounts add up? Isn't 25% + 10% just 35% off?
No — the second discount applies to the already reduced price, not the original. On an $80 item, 25% off brings it to $60, and then 10% off that $60 takes away $6, not $8. You end up at $54, which is 32.5% off the original, not 35%. The bigger the discounts, the wider this gap gets, which is why "extra percent off" promotions sound better than they are.
Is a bigger percentage off always the better deal?
Not necessarily. A percentage only tells you the size of the markdown, not the final cost — 40% off an inflated price can still cost more than 20% off a fair one. Compare the actual final prices, and for groceries or household goods compare unit prices (price per ounce, per load, per count) instead. A discount is only a deal if the price you pay is lower than what you'd pay elsewhere.
Do stores apply sales tax before or after the discount?
In most US states, sales tax is calculated on the discounted price you actually pay — the amount after store discounts and markdowns come off. That's how this calculator works. Coupons can be an exception: some states tax the pre-coupon price when a manufacturer coupon is used, because the store is reimbursed for it, while store coupons usually reduce the taxable amount. Your receipt will show how your state handled it.
What is keystone pricing, and are "original prices" real?
Keystone pricing is the retail practice of setting the ticket price at roughly double the wholesale cost, which leaves room for frequent "sales." Many advertised original prices are anchor prices — reference points designed to make the discount feel bigger — and some items sell at the "sale" price most of the year. The percentage off matters less than whether the final price is genuinely competitive, so compare across stores when the purchase is significant.