About the Percentage Calculator
The percentage calculator helps you find percentages, compare values, add or subtract a percentage, and measure percentage change. It is useful for discounts, tax, tips, price changes, grades, statistics, and everyday comparisons.
What Is a Percentage?
A percentage is a number expressed as a part of 100. For example, 25% means 25 out of 100, which is the same as 0.25 or one quarter.
Common Percentage Calculations
- X% of Y: finds a portion of a number, such as 15% of 200.
- X is what % of Y: compares one value to another as a percentage.
- X is Y% of what: finds the original whole when you know the part and the percentage.
- Increase or decrease: adds or subtracts a percentage from a base value.
- Percentage difference: compares two values relative to their average.
How to Use the Percentage Calculator
Choose the card that matches your question, enter the X and Y values, set decimal places if needed, and select OK. The calculator shows the result and the formula used for the calculation.
Formula and Worked Example
To find X% of Y, use X / 100 x Y. For example, 15% of 240 is 15 / 100 x 240 = 36. For a percentage increase, multiply the starting value by 1 + X / 100; increasing 80 by 25% gives 80 x 1.25 = 100.
Important Limits
Percentage change needs a non-zero starting value. A move from 0 to 10 cannot be expressed as a finite percentage increase, and percentage difference is not the same measure as percentage change.