Percentage Calculator
Calculate percentages, percentage changes and reverse percentages.
How to calculate percentages
A percentage expresses a number as parts per hundred. This calculator handles common percentage questions.
Percentage formula
Result = Y × X ÷ 100
Example
20% of 150 is 30 because 150 × 20 ÷ 100 = 30.
Common percentage calculations
Percentage problems usually fall into three patterns: finding a percentage of a number, finding what percentage one number is of another, and reversing a percentage to recover an original value. Keeping the base value clear is the most important step because the same two numbers can produce different answers depending on which value is treated as the reference.
When reverse percentage is useful
Reverse percentage is useful when you know a final price after a discount or tax change and need to estimate the original amount. For example, if a price after a 20% discount is known, the discounted value represents 80% of the original price rather than a simple subtraction from an unknown base.
Frequently Asked Questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100.
How do I calculate percentage change?
Subtract the old value from the new value, divide by the old value, then multiply by 100.
What is the difference between percentage and percentage points?
A percentage measures a relative share or change. Percentage points describe the direct difference between two percentage values, such as 20% to 25% being an increase of 5 percentage points.
Why does a percentage increase followed by the same percentage decrease not return to the starting value?
The second change is applied to a different base. For example, increasing 100 by 20% gives 120, while decreasing 120 by 20% gives 96.