Quick start
- Enter the original price, for example 120.
- Enter the discount percentage, such as 25.
- Enter the tax rate, or 0 if prices already include tax.
How the final price is worked out
First the discount comes off: 120 × 0.25 = 30, so the sale price is 90. Then tax is added on the sale price: 90 × 0.15 = 13.50. The total to pay is 103.50, and you save 30 compared with the original price before tax.
Does the order of discount and tax matter?
For the final total, no. 120 × 0.75 × 1.15 and 120 × 1.15 × 0.75 both give 103.50, because multiplication can be done in any order. What changes is how much tax you pay in total, which is lower when tax is charged on the discounted price.
Stacked discounts
"30% off, plus an extra 20% off" is not 50% off. The second discount applies to the reduced price: 100 → 70 → 56, which is 44% off in total.
Comparing two offers
Buy one get one half price is a 25% discount per item if you buy two. 3 for the price of 2 is about 33% off. Turning every offer into a single percentage makes them easy to compare.
Common questions
How do I work out the discount percentage from two prices?
Subtract the sale price from the original, divide by the original and multiply by 100. 80 down to 60 is 25% off.
What if tax is already included?
Set the tax rate to 0.
Is 'up to 70% off' reliable?
It only means some items reach 70%. Check the percentage on the item you want.