Discount Calculator

How It Works

A discount takes a percentage off the original price, and the sale price is what is left: sale price = original price × (1 − discount ÷ 100). Put another way, a 25% discount means you pay the other 75% — so a 25% discount on an $80 item leaves you paying $80 × 0.75 = $60, and you save $20. Thinking in terms of what you pay rather than what is taken off makes it easier to compare deals at a glance: 30% off means paying 70 cents on every dollar, and 50% off means paying half.

Things get more interesting when a second discount is stacked on top of the first — a coupon applied to an already-reduced item, or a clearance markdown followed by an extra percentage off at the till. The second discount is taken from the already discounted price, not the original one, so the two percentages do not simply add up. The combined discount is 1 − (1 − first discount) × (1 − second discount): 25% off plus an extra 10% off works out to 1 − 0.75 × 0.90 = 32.5% off in total, not 35%. The order of the two discounts makes no difference — 10% off followed by 25% off gives exactly the same $54 final price on an $80 item — because multiplication works the same in either order.

Sales tax is the last piece, and it is normally charged on the discounted price — the amount you actually pay — which means a discount saves you tax as well as sticker price. At 8% tax, an item reduced to $54 attracts $4.32 of tax, for a final total of $58.32. A few places handle this differently, so it is always worth a glance at the receipt. One more comparison is worth making before you buy: a fixed-amount coupon and a percentage coupon are not the same deal. On an $80 item, $10 off beats 10% off, because 10% of $80 is only $8 — but on a $250 item, 10% off saves $25 and beats the $10 coupon easily. Which one wins depends entirely on the price.

Common discounts on a $100 item:

Worked Example

An $80 shirt is marked 25% off, and you have a coupon for an extra 10% off the sale price. The first discount takes $80 down to $80 × 0.75 = $60. The coupon then takes 10% off $60, which is $6, leaving $54. Your total saving is $80 − $54 = $26, which works out to 32.5% off the original price — not 35%. If sales tax of 8% applied, it would be charged on the $54, adding $4.32 for a final total of $58.32.

Now a bigger purchase: a $1,200 laptop is on sale at 30% off, and you have a 5% coupon for the checkout, with 6% sales tax. The 30% discount takes $1,200 down to $840. The 5% coupon is taken from $840, not $1,200, so it saves $42 and leaves $798. Tax of 6% on $798 adds $47.88, for a final total of $845.88. Your total saving is $1,200 − $798 = $402, or 33.5% off — less than the 35% the two discounts seem to promise. A genuine single 35% discount would have taken the laptop to $780 before tax, saving $420, so the stacked offer is $18 worse than the headline suggests.

Assumptions

• Stacked discounts multiply, they do not add. The second discount is applied to the price after the first discount, which is how retailers apply coupons to sale items.
• Tax is charged on the discounted price at a single flat rate, which is the usual practice in most US states. A small number of jurisdictions tax the pre-discount price instead.
• No shipping, handling or other fees are included — the result is the price of the item plus tax only.
• No minimum-spend or exclusion rules are modelled. Real coupons often exclude certain brands or require a minimum purchase; this calculator assumes the discount applies to the full price you enter.
• The "original price" is taken at face value. The calculator does not check whether an item was ever actually sold at its listed original price — a sale price is only a bargain relative to what the item normally sells for.
• Results are rounded to the nearest cent. A retailer's till may round differently by a cent or two.

No external rates are used on this page — every figure is calculated from the numbers you enter. Last reviewed: 13 November 2026.

How to Use This Calculator

Enter the original price and the discount percentage to see the sale price and your savings straight away — results update as you type, so there is nothing to submit. The breakdown underneath the headline result shows the price after each discount, the total amount saved and the effective discount percentage, so you can see exactly how the final figure was reached.

Add a second discount for a stacked coupon or an extra markdown at the till: it is applied to the already-discounted price, and the breakdown shows the price after each step. Add your sales tax rate for the final checkout total; tax is charged on the discounted price. Leave either field at 0 to skip it. The Reset button restores the example values — an $80 item at 25% off with a 10% coupon — if you want to start over.

Tips and Practical Advice

Compare final prices, not headline percentages. A 20% discount on a $200 item saves $40, while a 30% discount on a $100 item saves $30 — the smaller percentage is the bigger saving in dollars. Whenever two deals compete, work out what each one actually costs at the till, after every discount and after tax, and compare those numbers.

Do the maths on stacked offers before you celebrate them. Two 20% discounts in a row equal 36% off, not 40%, because the second 20% is taken from a smaller number. And "up to 50% off" in a sale usually means only a few items carry the top discount — the item you want may be 10% off. Enter the real discount for the item in front of you, not the one on the banner.

Check the receipt, not just the shelf edge. Tax should normally be charged on the discounted price, so a big discount saves you tax too — if a receipt shows tax on the pre-discount price, that is unusual and worth questioning. The same goes for "buy one, get one free": it is 50% off two items, which is only a bargain if you actually wanted both. A discount on something you would not have bought is not a saving, whatever the percentage says.

Frequently Asked Questions