Question 1

How do you calculate percentage off?

Accepted Answer

Multiply the original price by the discount percentage, then subtract. $90 × 20% = $18 off, so the sale price is $72.

Question 2

How do you find what percent one number is of another?

Accepted Answer

Divide the part by the whole and multiply by 100. 15 ÷ 50 × 100 = 30%.

Question 3

How do you calculate percentage increase or decrease?

Accepted Answer

Subtract the original from the new value, divide by the absolute original, and multiply by 100. From 80 to 100 is (100 − 80) ÷ 80 × 100 = 25% increase.

Question 4

What is the difference between percent change and changing a number by a percent?

Accepted Answer

Percent change compares two known values (old vs new). Changing a number by a percent applies a percentage to a starting value to create a new result. They use related formulas but answer different questions.

Question 5

How do you find the original price before a discount?

Accepted Answer

Divide the sale price by (1 minus the discount as a decimal). A $72 sale price after 20% off is $72 ÷ 0.80 = $90 original.

Question 6

Why do stacked discounts not simply add together?

Accepted Answer

Each new discount is taken off the already-discounted price, not the original. 20% off then 10% off equals 28% off in total, not 30%.

Question 7

Does tax apply before or after a discount?

Accepted Answer

In most U.S. stores, tax is calculated after the discount, so you only pay tax on what you actually pay. Use the tax order toggle above to see both scenarios.

Calculate percentages, sale prices, and percent-off deals fast.

Find a percentage of a number

How this calculator works

Common questions

Calculate percentages, sale prices, and percent-off deals fast.

Find a percentage of a number

How this calculator works

How percentage formulas are calculated

How percent change is calculated

How discounts are calculated

How stacked discounts work

Why tax order changes the final total