Calculating Percentages

While our percentage calculator is a handy way to solve your percentage problems, we'll explain the math involved in all of the calculations below.

How to Find Percentage of a Number

This section explains how to answer the question "What is p% of x?".

The formula to find the percentage of a number is:

p% * x = y

Example: What's 10% of 30? Using the percentage formula: p% * x = y:

1. For this example, our equation is 10% * 30 = y
2. To start, convert the percentage (p) to a decimal by removing the percent sign (%) and dividing the number by 100. For our example: 10 / 100 = 0.1 
3. To find y, multiply the decimal form of the percentage by x. In this case: 0.1 * 30 = 3

In the example above, y = 3. In other words, 10% of 30 is 3.

10% * 30 = y

0.1 * 30 = 3

How to Solve "x is p% of what?"

The formula for calculating "x is p% of what?" is:

x / p% = y

Example: 10 is 20% of what? using the formula x / p% = y:

1. For this example, our equation is 10 / 20% = y
2. To start, convert our percentage to a decimal by removing the percent sign and dividing it by 100. In this case, 20 / 100 = 0.2.
3. Divide x by the decimal form of the percentage: 10 / 0.2 = 50

In this example, 10 is 20% of 50.

10 / 20% = y

10 / 0.2 = 50

How to Solve "x is What Percent of y?"

The formula for calculating "x is what percent of y?" is:

x / y = p%

Example: 4 is what percent of 10? Using the formula: x / y = p%

1. For this example, our equation is 4 / 10 = p%
2. 4 divided by 10 = 0.4 Note: This is in decimal form!
3. To convert the decimal to a percentage, multiply 0.4 * 100 = 40%.

In this example, 4 is 40% of 10.

4 / 10 = p%

.4 * 100 = 40%

Other Useful Tools and Guides

• See our percent change calculator, percent increase calculator, and percent decrease calculator for the formulas and examples for these calculations.
• Though often confused with percent change, our percent difference calculator explains the distinction between the two calculations and explains the formula for percentage difference.
• Use these calculators to convert a fraction to a percentage or a percentage to a fraction.