Discount Calculator
Enter the original price and the discount percentage. Add an extra discount if a second one applies at the till. The calculator gives the sale price, how much you save and the total discount the two make together.
Answer
Sale price
60.00
You save 20.00.
- you save
- 20.00
- total discount
- 25%
Check the work
Every line comes from the same calculation as the answer.
sale price = price × (1 − discount) × (1 − extra)
| after discount | 80.00 × (1 − 0.25) | 60.00 |
|---|---|---|
| you save | 80.00 − 60.00 | 20.00 |
| total discount | 20.00 ÷ 80.00 × 100 | 25% |
How it works
A discount takes a percentage off the price. 25% off 80 removes a quarter of 80, which is 20, leaving 60. Put another way, you pay 75% of the price: 80 × 0.75 = 60.
When a shop offers a second discount — an extra 10% at the till, or a coupon on a sale item — it almost always applies to the already-reduced price. 20% off and then 10% off does not make 30% off: 100 becomes 80, and 10% off 80 is 72, a total saving of 28%.
The effective discount line shows that combined percentage, so you can compare a stacked offer with a single one. Prices here are before any sales tax; if tax is added at the till, it applies to the sale price.
Formula
sale price = price × (1 − discount ÷ 100) × (1 − extra ÷ 100)
Each discount multiplies the price by the share that remains; a second discount multiplies the reduced price.
Worked examples
- Try these numbers
25% off a price of 80
- You pay 100% − 25% = 75% of the price.
- 80 × 0.75 = 60.
- You save 80 − 60 = 20.
The sale price is 60; you save 20.
- Try these numbers
20% off, then an extra 10% off 100
- After 20% off: 100 × 0.8 = 80.
- After a further 10% off: 80 × 0.9 = 72.
- You save 28, which is 28% of 100.
You pay 72 — a total discount of 28%, not 30%.
- Try these numbers
Half price, then half off again
- 40 × 0.5 = 20.
- 20 × 0.5 = 10.
- You save 30, which is 75% of 40.
You pay 10 — a total discount of 75%.
Inputs and results
- Original price
- The price before any discount, in your currency.
- Discount
- The percentage taken off, such as 25 for 25% off.
- Extra discount
- A second percentage taken off the reduced price. 0 if none.
- Sale price
- What you pay after the discounts, before tax.
- You save
- Original price minus sale price.
- Total discount
- The saving as a percentage of the original price.
When to use it
- Checking the price of an item in a sale before you reach the till.
- Comparing “20% off plus an extra 10%” with a flat “30% off” elsewhere.
- Working out how much a coupon saves on an already discounted item.
Common mistakes
- Adding two discounts together: 20% then 10% is 28% off, not 30%.
- Taking the discount off the sale price instead of the original price when a sign says “up to 50% off the original”.
- Confusing “you pay 75%” with “you save 75%”.
What it does not do
- It does not add sales tax or VAT; apply tax to the sale price separately.
- It does not handle fixed-amount coupons such as “10 off”, only percentages.
- It does not round to the shop’s pricing, such as prices ending in .99.
Method and assumptions
The first discount multiplies the price by (1 − discount ÷ 100); a second discount multiplies that result by (1 − extra ÷ 100). The saving is the original price minus the sale price.
The total discount is the saving divided by the original price, times 100. Money amounts are displayed to two decimal places.
Assumptions
- A second discount applies to the already-reduced price.
- Prices are before tax.
Edge cases
- A 0% discount leaves the price unchanged.
- A 100% discount gives a sale price of 0.
- Discounts above 100% are refused, because a price cannot go below zero.
Sources and corrections
This calculator uses an elementary formula, so it needs no outside data source. The method, the rounding rules and how a reported error is corrected are set out in the site standards.
Result looks wrong?
Send the inputs you used and the answer you expected. Every report is checked against the formula and its tests, and confirmed errors are corrected in public.