How to use the discount calculator
- 1Enter the original price.
- 2Pick a percentage off, or switch to an amount off.
- 3Tick Extra discount if you have a coupon on top of a sale.
- 4Add the sales tax rate to see the final amount at the checkout.
How the discount is worked out
For a percentage off, multiply the price by (1 − discount ÷ 100). 25% off 120 is 120 × 0.75 = 90, saving 30.
Stacked discounts multiply
A 25% sale with an extra 10% coupon is not 35% off. The coupon applies to the already reduced price: 120 × 0.75 × 0.90 = 81, a total discount of 32.5%. The calculator shows this effective discount so you can compare offers fairly.
Tax comes after the discount
In most places sales tax is charged on the price you actually pay, so the discount is applied first and tax added afterwards. Enter your local rate to see the checkout total.
Quick mental check
10% off is easy: move the decimal point one place left. 20% is double that, 5% is half of it, and 15% is the two added together.
Frequently asked questions
How do I calculate 20% off?
Multiply the price by 0.8. For 50, that is 40, a saving of 10.
Is 20% off plus 20% off the same as 40% off?
No. Two 20% discounts give 36% off in total, because the second applies to the reduced price.
Should tax be added before or after the discount?
Usually after. Tax is normally charged on the discounted price, but check your local rules.
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