April 18, 2024
Learn how to calculate percentage decrease accurately with this step-by-step guide. Tips and common pitfalls to avoid are also included, along with easy methods for calculating percentage decrease in Excel and real-world applications.


Percentage decrease is an important concept that is often used in finance, business, and many other fields. It is a measure of how much a value has decreased over a certain period, expressed as a percentage of the original value. Knowing how to calculate percentage decrease can help you make better decisions in many situations, from analyzing financial data to negotiating prices.

How to Calculate Percentage Decrease: A Step-by-Step Guide

The formula for calculating percentage decrease is:

Percentage decrease = (Original value – New value) / Original value x 100%

To use this formula, follow these steps:

  1. Subtract the new value from the original value.
  2. Divide the result by the original value.
  3. Multiply the result by 100 to convert it to a percentage.

For example, if the original value was $100 and the new value is $80, the calculation would be:

Percentage decrease = (100 – 80) / 100 x 100% = 20%

Understanding Percentage Decrease: Tips for Accurate Calculations

To calculate percentage decrease accurately, it’s important to keep a few key tips in mind:

  • Start with the original value: The percentage decrease is always based on the original value, not the new value. Make sure you are subtracting the new value from the original value, not the other way around.
  • Be mindful of the order: The order in which you subtract the values matters. If you subtract the new value from the original value instead of the other way around, you will get a positive percentage increase instead of a percentage decrease.
  • Avoid common mistakes: Common mistakes include forgetting to multiply the result by 100 or using the wrong formula altogether.

Easy Methods for Calculating Percentage Decrease in Excel

Excel provides built-in functions that make it easy to calculate percentage decrease. The two functions you can use are:

  • Percentage decrease between two numbers: This function calculates the percentage decrease between two values.
  • Percentage decrease over time: This function calculates the percentage decrease over a period of time.

To calculate percentage decrease using these functions, follow these steps:

  1. Select the cell where you want the result to appear.
  2. Type the equal sign (=) followed by the name of the function.
  3. Enter the range of cells containing the values you want to use.
  4. Press Enter to calculate the percentage decrease.

For example, the formula for the percentage decrease between two values in cells A1 and B1 is:


Calculating Percentage Decrease: Common Pitfalls to Avoid

When calculating percentage decrease, there are a few common pitfalls to avoid:

  • Using the wrong formula: Make sure you are using the correct formula for calculating percentage decrease, which is (Original value – New value) / Original value x 100%.
  • Forgetting to multiply by 100: To convert the result to a percentage, you need to multiply it by 100.
  • Using the wrong values: Make sure you are using the correct values for the original and new values. If you mix them up, you will get the wrong result.
  • Assuming negative percentage decrease is impossible: Negative percentage decrease means the value has increased instead of decreased. It’s important to recognize this possibility and interpret the result accordingly.

A Comprehensive Guide to Percentage Decrease: From Basic Concepts to Real-World Applications

Percentage decrease is used in many real-world scenarios, from analyzing financial data to negotiating prices. Here are some examples:

  • Personal finance: Percentage decrease can help you evaluate investment performance, track budget spending, and compare prices between two periods.
  • Business: Percentage decrease can help you analyze sales performance, monitor profit margins, and assess inventory levels.
  • Other areas: Percentage decrease can be used in many other fields, from healthcare to education.

In addition, there are some advanced topics related to percentage decrease, such as compound percentage decrease. This is when the percentage decrease is applied over multiple periods, resulting in a cumulative effect that is greater than the original percentage decrease. To calculate compound percentage decrease, you can use the formula:

Compound percentage decrease = (1 – (New value / Original value))n x 100%

Where n is the number of periods over which the decrease is applied.


Calculating percentage decrease is an important skill that can be used in many situations. By following the steps outlined in this guide and avoiding common pitfalls, you can accurately calculate percentage decrease and use this information for decision-making. Whether in personal finance, business, or other areas, percentage decrease is a powerful tool that can help you achieve your goals.

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