From percent off to the price you pay
A percentage discount is just a fraction of the original price, and the whole point is to convert that fraction into something concrete. Going forward, you turn a percent into a final price; going backward, you turn two prices into the percent that separates them. Both directions use the same simple relationship, so once you can move one way you can always move the other — handy for spotting whether an advertised markdown is as deep as the sign claims. Where it gets interesting is stacking a second percent off and adding tax, because that is where the headline number and the register total stop matching.
The formulas
Sale price = Original × (1 − discount ÷ 100)
Discount % = (Original − Sale) ÷ Original × 100
The first turns a percentage into the price you pay; the second turns two prices into the percentage between them. For a $60 item at 30% off, the top line gives $60 × 0.70 = $42; given $60 and $42, the bottom line gives (60 − 42) ÷ 60 × 100 = 30%. Stack a second percent off and it multiplies onto the sale price; sales tax is then added to whatever remains.
What makes this calculator different
- Both directions at once. Convert a percent into the price you pay, and the savings in dollars, without doing the decimal math in your head.
- Stacked percentages handled correctly. A second percent off the sale price compounds rather than adds, and the true combined discount is shown beside the figure most people assume.
- Tax on the right number. Sales tax is applied to the discounted price, so the total reflects what you actually hand over.
- Shareable and reversible. Every scenario lives in the URL, and the same formula works backward to recover the original price from a sale price.
Frequently asked questions
What is a percentage discount and how is it calculated?+
A percentage discount is a price reduction expressed as a share of the original price rather than a fixed dollar amount. To calculate the dollars off, multiply the original price by the discount written as a decimal — a 30% discount is 0.30. On a $60 item that is $60 × 0.30 = $18 off. Because the percentage scales with the price, the same percentage saves more on an expensive item than on a cheap one.
How do I find the final price after a percentage discount?+
Subtract the amount off from the original price, or use the shortcut of multiplying the original price by one minus the discount. For a 30% discount on $60: either $60 − $18 = $42, or $60 × (1 − 0.30) = $60 × 0.70 = $42. The shortcut is faster because it gets you to the price you actually pay in a single step. If sales tax applies, add it to this discounted price, not the original.
How do I calculate the percentage discount from an original and a sale price?+
Subtract the sale price from the original price, divide by the original price, and multiply by 100. The formula is discount % = (original − sale) ÷ original × 100. If a $60 item is marked down to $42, that is (60 − 42) ÷ 60 × 100 = 18 ÷ 60 × 100 = 30% off. This is the direction to use when a tag shows two prices but not the percentage, or when you want to compare two markdowns fairly.
Can I combine two percentage discounts?+
You can, but they compound rather than add, because the second discount comes off the already-reduced price instead of the original. A 30% discount followed by an extra 10% off the sale price is not 40% off — it is 1 − (0.70 × 0.90) = 1 − 0.63 = 37% off. Two discounts of a% and b% always combine to less than a + b. The effective combined percentage is the number that actually matters for what you pay.
How do I reverse a percentage discount to find the original price?+
Divide the sale price by one minus the discount as a decimal. If you paid $42 after a 30% discount, the original price was $42 ÷ (1 − 0.30) = $42 ÷ 0.70 = $60. This works because the sale price equals the original times 0.70, so dividing undoes the multiplication. It is useful for checking whether an advertised "original" price is genuine or for working backward from a receipt.
Disclaimer: This calculator is for educational purposes only. How discounts, coupons, rebates, and sales tax are applied varies by retailer and jurisdiction. It is not financial advice.