The **MathBlog percentage change calculator** is a tool that automates calculating the percentage change between two values, providing clear understanding of the increase or decrease from an initial value to a final value.

## Percentage change calculator

Percent change formula

\( \frac {(P2 - P1) \times 100}{|P1|} \)

## What is Percent Change?

Percent change is a mathematical concept that quantifies the change from one number to another, expressed as a percentage. It is particularly useful for highlighting the relative change between an initial value (old number) and a final value (new number). The percent change can be positive, indicating an increase, or negative, indicating a decrease.

For example, if you have 10 apples and this number increases to 20 apples, the percentage change is a 100% increase.

### When to Use the Percent Change Calculator

This calculator is ideal for scenarios where you have distinct starting and ending values. Some common applications include:

**Finance**: Track investment growth or decline, compare financial performance over different periods.**Science**: Measure changes in experimental data, chemical concentrations, or rates of reaction.**Population Studies**: Calculate population growth rates or demographic changes.

### How to Calculate Percent Change

The percent change formula is:

\( ( \frac{\text{New Value} – \text{Old Value}}{\text{Old Value}} ) \times 100 \)

### Example Calculation

Suppose the population of a small town increases from 1,000 to 1,200 over a year. To find the percentage change:

\( Percent Change= (\frac {1200−1000}{1000} ) \times 100=20% \)

This indicates a 20% increase in the population.

### Practical Tips and Common Pitfalls

**Order Matters**: Ensure you correctly identify the initial (old) and final (new) values.**Positive and Negative Changes**: A positive result signifies an increase, while a negative result indicates a decrease.**Decimal Precision**: Depending on the context, you might need to round your result to a certain number of decimal places for clarity.