Everyday

🏷️ Discount Calculator

Three ways to do discount maths: take a percentage off a price, work out the discount between an original and a sale price, and go backwards from a sale price to the original.

1. Take a percentage off a price

—You pay
—You save

—

2. What discount did I actually get?

—Discount
—You saved

—

3. What was the original price?

—Original price
—You saved

—

About the Discount Calculator

Discount maths is the most common piece of mental arithmetic people get wrong, and it is not the shopper's fault — the two-step version (find the saving, then subtract) is easy to muddle under time pressure, and 'extra 20% off sale prices' is genuinely not the same as 40%.

This calculator covers all three questions that actually come up: the sale price from a percentage, the percentage from two prices, and the original price when all you can see is the sale ticket. Results are plain numbers, so they work in any currency.

Frequently asked questions

How do I work out 20% off?

Multiply the price by 0.20 to get the saving, then subtract it — or multiply by 0.80 to get the final price in one step. An item priced 120 with 20% off costs 96 and saves 24.

Is 20% off and then another 20% off the same as 40% off?

No, and this is the trick that shop promotions rely on. Successive discounts multiply: 0.80 × 0.80 = 0.64, so the real total discount is 36%, not 40%. Run the first result back through the calculator to check any 'extra 20%' offer.

Why does the reverse mode need a discount below 100%?

Because the original price is found by dividing by (1 − rate). At exactly 100% off that divisor is zero, so the original price is undefined; above 100% the formula returns a negative price. Real discounts are always below 100%.

Related tools

🎂

Age Calculator

Your exact age in years, months and days — plus a countdown to your next birthday.

💯

Percentage Calculator

Percent of a number, what percent X is of Y, and percentage increase or decrease.

📅

Date Calculator

Days between two dates (with business days), or add / subtract days, weeks, months and years.

🧾

Invoice Generator

Create a clean, professional invoice and save it as PDF — free, no signup.