Discount Calculator
Calculate sale prices, savings, and final cost after single or multiple discounts. Supports stacked discounts and shows your total savings at a glance.
Calculator verified • Last updated: August 2026
Price & Discount
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Two discounts stack multiplicatively, not additively — see "You Save" and "Total Discount" above for the real combined effect.
Quick Reference — Common Discount Percentages
| Discount | Sale Price | You Save |
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How to Calculate a Discount
The formula is straightforward: multiply the original price by (1 minus the discount as a decimal).
Sale Price: the discounted price you actually pay.
Original Price: the item's price before any discount.
d: the discount as a decimal (for example, 25% = 0.25).
For a 25% discount on a 120-dollar item: 120 × (1 − 0.25) = 120 × 0.75 = 90 dollars. Your savings is simply the original price minus the sale price — in this case, 30 dollars.
Double Discounts Explained — Why 20% + 10% Isn't 30%
This trips up a lot of shoppers: a 20% discount followed by an additional 10% off does not equal 30% off the original price. The second discount applies to the already-discounted price, not the original:
d1: the first discount, as a decimal.
d2: the second discount, applied after the first, as a decimal.
This is not the same as — simply adding the two percentages together. So 100 dollars at 20% off becomes 80 dollars, and 10% off 80 dollars is 8 dollars, for a final price of 72 dollars — a combined discount of 28%, not 30%. Stacked discounts are always slightly less generous than simply adding the percentages together.
How to Calculate Sales Tax on Discounted Items
Sales tax is almost always calculated on the price you actually pay — the discounted sale price — not the original sticker price. Multiply the sale price by your local tax rate to get the tax amount, then add it to the sale price for your true final cost. This calculator handles that automatically when you enter a tax rate above 0%. For example, a 60-dollar item at 25% off becomes a 45-dollar sale price; at an 8% local tax rate, that adds 3.60 dollars in tax, for a final cost of 48.60 dollars — still well below the original 60 dollars, even after tax is added back in.
Tips for Smart Shopping — When Discounts Are Real vs. Inflated
Some "sales" inflate the original price first so the discount looks bigger than it actually is — compare against the item's typical price history when possible, not just the sticker's crossed-out number. Stacked discounts (a sale price plus a coupon, for example) can be genuinely great deals, but always calculate the real final price rather than assuming the percentages just add up.
Common Discount Math Mistakes
Adding stacked discount percentages together, as covered above, is the single most common error and one retailers rarely correct since it tends to favor them. Applying sales tax to the original price instead of the discounted price is another frequent mix-up, one that (unlike the previous one) usually costs the shopper by overstating the true final cost when estimating it by hand. Confusing "percent off" with "percent of the original price remaining" also trips people up — a 70% discount leaves you paying 30% of the original price, not 70% of it.
Discount Terms You Should Know
Markdown — another term for a discount, most common in retail contexts; reducing an item's price from its original listed value.
Loss Leader — a product priced at a steep discount (sometimes below cost) specifically to draw customers into a store, where they're likely to also purchase full-price items.
Coupon Stacking — combining multiple discounts (a sale price plus a coupon plus a loyalty discount, for example) on a single purchase, where retailer policy permits it.
MSRP — Manufacturer's Suggested Retail Price, the baseline "original" price a percentage discount is often calculated from.
Frequently Asked Questions
Is a double discount the same as adding both percentages?
No. A 25% discount followed by an additional 10% discount is not 35% off — the second discount applies to the already-reduced price. Two 25% discounts equal 43.75% off total, not 50%.
Is sales tax calculated before or after the discount?
In almost all cases, sales tax is calculated on the discounted sale price, not the original price. This calculator applies tax after the discount, matching standard retail practice.
How do I calculate the original price from the sale price?
Check the "Reverse: I know the sale price" box and enter the sale price you already know instead of the original price. The calculator divides it by (1 minus the discount as a decimal) automatically — for an item that's 60 dollars after a 25% discount, that's 60 divided by 0.75, or 80 dollars original price.