Percentage Decrease Calculator


Percentage Decrease Calculator

Welcome to the wild and wacky world of percentage decreases! Strap in, because we’re about to make numbers fun. Or at least, less terrifying.

What is Percentage Decrease?

Percentage decrease is a measure of how much a quantity has decreased relative to its original size. It’s calculated by subtracting the new quantity from the original, dividing by the original quantity, and then multiplying by 100. Here’s the formula in all its glory:

Percentage Decrease = ((Original - New) / Original) * 100

Categories of Percentage Decrease

Category Range
Small decrease 0% – 10%
Moderate decrease 10% – 25%
Large decrease 25%+

Examples of Percentage Decrease Calculations

Initial Quantity Final Quantity Percentage Decrease
200 lbs 180 lbs ((200-180)/200)*100 = 10%
10 miles 8 miles ((10-8)/10)*100 = 20%

Ways to Calculate Percentage Decrease

Method Advantages Disadvantages Accuracy
Using a calculator Fast, easy Requires a calculator High
Mental math No tools required Difficult with large numbers Low to moderate

Evolution of Percentage Decrease Calculation

Time Period Method Used
Ancient times Mental estimation
Middle ages Use of counting boards
Modern day Digital calculators

Limitations of Percentage Decrease Calculation

  1. Dependent on initial quantity: Higher initial quantities can lead to larger percentage decreases for the same absolute decrease.
  2. Not useful for negative quantities: Percentage decrease is not defined for negative quantities.

Alternative Methods

Method Pros Cons
Absolute decrease Simple, easy to understand Does not account for the size of the original quantity


  1. How do I calculate percentage decrease? Subtract the new quantity from the original, divide by the original quantity, and multiply by 100.
  2. What is a small percentage decrease? A small percentage decrease is considered to be between 0% and 10%.
  3. What is a moderate percentage decrease? A moderate percentage decrease is considered to be between 10% and 25%.
  4. What is a large percentage decrease? A large percentage decrease is anything over 25%.
  5. Can I calculate percentage decrease without a calculator? Yes, you can use mental math, but it may be difficult with large numbers.
  6. What’s the difference between absolute decrease and percentage decrease? Absolute decrease is a simple subtraction, while percentage decrease takes into account the original quantity.
  7. Can I calculate percentage decrease if the initial quantity is negative? No, percentage decrease is not defined for negative quantities.
  8. How has the calculation of percentage decrease evolved over time? In ancient times, mental estimation was used. During the Middle Ages, counting boards were used. Today, digital calculators are used.
  9. What are the limitations of percentage decrease calculation? It’s dependent on initial quantity and not useful for negative quantities.
  10. Where can I learn more about percentage decrease calculation? You can visit the U.S. Bureau of Labor Statistics website for detailed explanations.


  1. U.S. Bureau of Labor Statistics: Offers detailed explanations on calculating percentage decrease.