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Percentage Change Calculator

You can use our calculator to work out the percentage increase or decrease from one value to another. Or, scroll down to read our explanation of what percentage change is and how to calculate it.

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.

Table of contents:

Understanding percentage change

Let's begin by discussing what percentage change is, and we can then go through how to calculate it, with some examples to help.

Percentage change is a fundamental mathematical concept that allows us to measure and compare the relative difference between two values. Performing this calculation can help us see how much something has increased or decreased in value or quantity over time.

You'll find percentage change figures widely referenced in fields such as finance, economics and statistics. For example, you may find yourself looking at a statement for an investment and wondering what the percentage increase (in interest) has been compared to your initial investment.

You'll also find occasions in everyday life where calculating percentage change is useful. For example, there may be a sale at your local electrical store, and you might find yourself wanting to compare the price of an item before and after a discount, to evaluate the discount.

How to calculate percent change

To calculate percentage change, subtract your initial value from your final value to get the difference, and then divide that figure by the initial value. Multiply the result by 100 to get the percentage: (finalValue − initialValue) / initialValue × 100.

Here's the step-by-step process for calculating percentage change:

  1. Determine the initial value (old value) and the final value (new value).
  2. Subtract the initial value from the final value: final value - initial value.
  3. Divide the resulting figure by the initial value.
  4. Multiply the result by 100 to convert to a percentage.

The result from above represents the percentage change between the initial value and the final value. If the result is positive, it indicates an increase, while a negative result signifies a decrease.

Let's have a look at this as a formula...

Percentage = (finalValue - initialValue) / initialValue × 100

Using this formula, when numbers go up, you can work out the percentage increase. When numbers go down, you can work out the percentage decrease. You need to make sure you do the calculation in the correct order, using PEMDAS. So, numbers within brackets first.

Percentage discount example

Example scenario 1: You are shopping for a new laptop, and you come across a model that initially costs $1,000. However, you notice that it is on sale at a discounted price. You want to calculate the percentage change in price.

First, let's get our values:

  • Initial price: $1,000 (old value).
  • Discounted price: $800 (new value).

Now, we can calculate the percentage change:

  • Subtract the initial price from the discounted price: $800 - $1,000 = -$200.
  • Divide the result by the initial price: -$200 / $1,000 = -0.2.
  • Multiply the resulting figure by 100 to convert it into a percentage: -0.2 * 100 = -20%.

The calculated percentage change is -20%, indicating a 20% discount on the original price.

Percentage increase example

Example scenario 2: You find out that your landlord is increasing your rent from $650 to $700 per month and you want to know what the percentage increase is. Let's work it out...

  • New number - old number = increase
  • $700 (new rent) - $650 (old rent) = $50 increase
  • (increase / old number) × 100
  • $50 (increase) / $650 (old number) = 0.0769.
  • Then × 100 = 7.69% increase

The increase in rent in our example works out at 7.69%.

To check your calculation, you can use calculator at the top of the page. Simply enter your 650 figure into the first box and 700 into the second.

I hope you found our calculator and article useful. You can learn more about how to calculate percentage change in our article here. And, it's well worth bookmarking our main percentage calculator for everyday percentage calculations.

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