How to Calculate a Discount

Updated October 24, 2026

To find a sale price, multiply the original price by 1 minus the discount: $80 at 25% off is $80 × 0.75 = $60. To find the original price from a sale price, divide instead: $60 ÷ 0.75 = $80. And two discounts in a row don't add up: 20% off and then 10% off is 28% off, not 30%.

The three discount questions

1. What's the sale price?

For a quick estimate in your head, find 10% by moving the decimal point (10% of $80 is $8), then scale: 20% is $16, 25% is $20, 30% is $24. On coolca.lc's main calculator you can type it directly: $80 − 25% gives $60.

2. What was the original price?

If a tag says $60 after 25% off, adding 25% back gives $75, which is wrong: the 25% was taken from the original price, not from $60. Divide by 1 minus the discount:

3. How much off is it really?

When a store shows two prices, "was $80, now $60", find the percent off by dividing the savings by the original price:

It's worth checking. Signs round generously, and "up to 50% off" usually means a few items are 50% off and most are less.

Stacked discounts and coupons

"Take an extra 10% off sale prices" is one of the most misread offers in retail. Each discount is taken from the price after the one before it, so percentages multiply rather than add:

The order of two percentages doesn't change the result: 20% then 10% and 10% then 20% both come to $72. But the order of a percentage and a dollar coupon does:

• 20% off $100, then a $5 coupon: $80 − $5 = $75.
• A $5 coupon, then 20% off: $95 × 0.8 = $76.

Percentage first, then the dollar amount, is better for you, and it's the order most receipts apply them in. The Stacked Discounts Solver uses that order: up to two percentages, then a coupon, with the total percent off and the amount saved spelled out.

Comparing deals

• Buy one, get one 50% off is 25% off each item when you buy two: you pay 1.5 prices for 2 items.
• Buy one, get one free is 50% off each item, but only if you actually want two.
• Bigger packages aren't always cheaper per item. Compare the price per unit with the Unit Price Solver.
• Sales tax is normally charged on the discounted price, so a discount saves you the tax on the amount taken off too. See how sales tax works.

Using the Discount Solver

coolca.lc's Discount Solver has three slots: Price, Off % and Sale. Fill in any two and the third shows SOLVE, so it answers all three questions above.

1. Open Discount.
2. Type the original price, such as 80, and tap Price.
3. Type the discount, such as 25, and tap Off %.
4. Tap Sale, which shows SOLVE.

To find the original price, fill in Sale and Off % and tap Price. To find the real percent off, fill in Price and Sale and tap Off %.

Stacked Discounts

The Stacked Discounts Solver has five slots: Price, Off %, Then %, Coupon $ and Sale. Then % and Coupon $ are optional; leave either empty to skip it.

Questions