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Percentage Calculator

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Disclaimer: Whilst every effort has been made in building our calculator tools, we are not to be held liable for any damages or monetary losses arising out of or in connection with their use. Full disclaimer.

Use our percentage calculator to work out increases, decreases or percentage differences. Common uses include calculating tax, statistics, savings increases, and tips on a restaurant bill.

What is a percentage?

A percentage is a number that expresses a portion or proportion of a whole in relation to 100. As an example, if 80% of a class passed an exam, it means that 80 out of every 100 students in the class achieved a passing grade.

Percentages are represented by the symbol "%" and provide a standardized method to compare quantities or indicate changes. You'll find them used in fields such as finance and statistics, and you'll likely use them within everyday situations, such as splitting a bill, calculating a gratuity or working out a discount.

Let's take a look at how to calculate percentages.

What is the percentage of Y?

To calculate a percentage based upon a part (X) and a total (Y), divide the value of the part (X) by the total or whole amount (Y). Then, multiply the result by 100.

As an example, if you want to find what percentage 15 is of 300, you would divide 15 by 300, resulting in 0.05. Multiplying 0.05 by 100 gives you 5%.

  1. Divide the part figure by the whole figure. So, in the case of our example: 15/300 = 0.05.
  2. Convert this into a percentage figure by multiplying by 100. So, 0.05 x 100 = 5.
  3. This gives you your answer. 15 is 5% of 300.

The formula for the calculation looks like this:

Percentage = (Part / Whole) × 100

You can find out more about how to calculate simple percentage increases and decreases in our article here.

Let's look at some other types of percentage calculation...

How to calculate X percent of Y

In order to explain how to do this calculation, we'll replace the X and Y with a couple of figures. Let's say the question is: What is 10% of 200?. Here's how to do it:

  1. Change the percentage figure into a decimal by dividing the figure by 100. So, 10% becomes 10/100 = 0.1.
  2. Multiply the decimal figure by the full amount. So, 0.1 x 200 = 20.
  3. This gives you your answer. 10% of 200 is 20.

The formula for this calculation looks like this:

Part = (X / 100) × Y

How to calculate a percentage increase or decrease

Continuing the theme, let's add some example figures into our calculation. Let's say the question is: What is the percentage increase from 40 to 68? We can use the percentage change calculator. Or we can work the calculation out manually...

  1. Subtract X from Y and then divide it by X. In the case of our example it would be (68-40) / 40. Note that we've put brackets around the first part to ensure this is done first (PEMDAS).
  2. (68-40) / 40 gives us a result of 0.7. To convert this into a percentage we multiply it by 100. So, 0.7 x 100 = 70.
  3. This gives you your answer. The percentage increase from 40 to 68 = 70%.

Here's the formula for this calculation:

Percentage = (Y - X) / X × 100

X is Y percentage of what number?

Let's again replace the X and Y with a couple of figures. Let's say the question is: 5 is 20% of what number?.

  1. Change the Y percentage figure into a decimal. We do this by dividing the figure by 100. So, 20% becomes 20/100 = 0.2.
  2. Divide our X figure by our Y figure. so, 5 / 0.2 = 25.
  3. This gives you your answer. 5 is 20% of 25.

Here's the formula:

Whole = X / (Y / 100)

To check your calculations, you can use the percentage calculator at the top of the page. I hope you've found our calculator and article useful.

Calculator by Alastair Hazell