Percentage Calculator
Use this calculator for three common percentage questions: finding a percentage of a number, finding what percentage one value is of another, and measuring percentage increase or decrease.
What is X% of Y?
The formula is (percentage ÷ 100) × number. For example, 20% of 150 is 30. This is useful for discounts, tax estimates, commissions, tips and simple budgeting.
What percentage is A of B?
Divide A by B and multiply by 100. If 30 people out of 120 complete a task, the completion rate is 25%. The same formula works for test scores, conversion rates, market share and progress toward a target.
Percentage change
Percentage change compares the difference with the original value: ((new − old) ÷ old) × 100. Moving from 100 to 125 is a 25% increase. Moving from 100 to 80 is a 20% decrease.
Percentage points are different
A move from 20% to 25% is an increase of 5 percentage points, but the relative percentage increase is 25%. This distinction matters when comparing rates such as conversion rate, interest rate or survey results.
Reverse percentage examples
If a sale price is $80 after a 20% discount, the sale price represents 80% of the original. Divide 80 by 0.80 to get an original price of $100. Reverse-percentage questions are common when working backward from discounts or markups.
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