How do I calculate a discount quickly in my head?

Ten percent is the decimal point moved one place, and everything else builds from it. 35% off 80 is 8 (10%) times 3 plus 4 (half of 10%), so 28 off, leaving 52.

Is the biggest percentage always the best deal?

Only against the same starting price. A 40% discount on an inflated list price frequently beats nothing at all, which is why the amount you actually pay is the number this page puts first.

Businesspricing

Discount Calculator

Discounted price with optional tax applied afterwards, and the effective discount once tax is counted.

Also called: percentage off calculator, sale price calculator.

You pay

1,749.3

You pay 1,749.3. A saving of 749.7 off 2,499, which is 30% of the original.

You save

749.7

Price after discount

1,749.3

Effective discount

30%

How this is calculated

Method and background

How this is calculated

The discount comes off first and tax goes on the reduced amount, which is the order almost every jurisdiction uses. The effective discount is measured against the original pre-tax price, so it is smaller than the headline once tax is included.

final = price * (1 - discount) * (1 + tax)

d: Discount as a decimal
t: Tax as a decimal

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

30% off 2499

Original price: 2,499
Discount (%): 30
Tax added afterwards (%): 0

You pay1,749.3

arithmetic identity

Open this example

with 18% tax on the reduced price

Original price: 2,499
Discount (%): 30
Tax added afterwards (%): 18

You pay2,064.17

arithmetic identity: 2499 x 0.7 x 1.18

Open this example

no discount

Original price: 2,499
Discount (%): 0
Tax added afterwards (%): 0

You pay2,499

degenerate case

Open this example

Frequently asked questions

How do I calculate a discount quickly in my head?: Ten percent is the decimal point moved one place, and everything else builds from it. 35% off 80 is 8 (10%) times 3 plus 4 (half of 10%), so 28 off, leaving 52.
Is the biggest percentage always the best deal?: Only against the same starting price. A 40% discount on an inflated list price frequently beats nothing at all, which is why the amount you actually pay is the number this page puts first.