Percentage Calculator

What Is a Percentage?

A percentage is a mathematical way to express a number as a fraction of 100. It’s used to show how one quantity compares to another, and it’s written with the percent sign (%) after the number—like 25%—or by spelling it out as “percent” or using “pct”.

You can think of percentages as another way to represent ratios, fractions, or decimals. For example:

• 35% is the same as 0.35 in decimal form

• It’s also equivalent to 35 out of 100 or 7/20 as a fraction

How to Calculate Percentages

To calculate a percentage, multiply a ratio or decimal by 100.

Example:
If 25 out of 50 students are male:
25 ÷ 50 = 0.5
0.5 × 100 = 50%

So, 50% of the class is male.

Basic Percentage Formula

You can calculate percentages using the formula:

P × V1 = V2

Where:

• P is the percentage (in decimal form)

• V1 is the base or original number

• V2 is the result after applying the percentage

Example:
Let’s say you want to find what percentage of 30 equals 1.5:
1.5 ÷ 30 = 0.05
0.05 × 100 = 5%

When solving manually, remember to convert decimals to percentages by multiplying by 100.

How to Calculate Percentage Difference

The percentage difference between two values shows how much they differ in relation to their average. Use this formula:

Percentage Difference =
|V1 − V2| ÷ ((V1 + V2)/2) × 100

Example:
Comparing 10 and 6:
|10 − 6| = 4
(10 + 6)/2 = 8
4 ÷ 8 = 0.5
0.5 × 100 = 50%

So, the difference between 10 and 6 is 50%.

How to Calculate Percentage Change

Percentage change tells you how much a value has increased or decreased from an original number. It’s used to show trends like price changes, growth rates, or discounts.

Formula:
|New Value − Original Value| ÷ Original Value × 100

You can also apply a percentage increase or decrease like this:

Increase Example:

Increase 500 by 10%:
10% = 0.1 (decimal)
500 × (1 + 0.1) = 550

Decrease Example:

Reduce 500 by 10%:
500 × (1 − 0.1) = 450

This method helps you quickly calculate how a value changes with any given percentage.