Percentage Change Calculator
Use this calculator to determine the percentage increase or decrease between two values.
How to Calculate Percentage Change: A Comprehensive Guide
Percentage change is a fundamental concept used across various fields, from finance and economics to science and everyday statistics. It quantifies the relative change between an old value and a new value, expressing this change as a percentage of the original value. Understanding how to calculate percentage change allows you to analyze growth, decline, and overall shifts in data more effectively.
What is Percentage Change?
At its core, percentage change measures the degree of change over time. It tells you how much a quantity has increased or decreased relative to its starting point. For instance, if a stock price goes from $100 to $120, it's a $20 increase. But expressing this as a percentage (20%) gives a clearer picture of the magnitude of that change, especially when comparing it to other changes.
The Formula for Percentage Change
The formula for calculating percentage change is straightforward:
Percentage Change = ((New Value - Original Value) / Original Value) * 100
Let's break down each component:
- New Value: This is the current or ending value.
- Original Value: This is the old or starting value.
- Difference (New Value – Original Value): This calculates the absolute change between the two values. A positive result indicates an increase, while a negative result indicates a decrease.
- Dividing by Original Value: This step normalizes the change, expressing it as a fraction of the starting point.
- Multiplying by 100: This converts the fraction into a percentage.
Step-by-Step Calculation Examples
Example 1: Percentage Increase (Sales Growth)
Imagine your company's sales increased from 200 units last month to 250 units this month.
- Original Value = 200
- New Value = 250
- Difference = 250 – 200 = 50
- Fractional Change = 50 / 200 = 0.25
- Percentage Change = 0.25 * 100 = 25% increase
This means your sales grew by 25%.
Example 2: Percentage Decrease (Population Decline)
A small town's population decreased from 10,000 residents to 9,500 residents over a decade.
- Original Value = 10,000
- New Value = 9,500
- Difference = 9,500 – 10,000 = -500
- Fractional Change = -500 / 10,000 = -0.05
- Percentage Change = -0.05 * 100 = -5% decrease
The town experienced a 5% population decrease.
Example 3: Stock Price Fluctuation
A stock you own was valued at $50 per share, and now it's $55 per share.
- Original Value = 50
- New Value = 55
- Difference = 55 – 50 = 5
- Fractional Change = 5 / 50 = 0.10
- Percentage Change = 0.10 * 100 = 10% increase
Your stock has increased by 10%.
Why is Percentage Change Important?
Percentage change provides context and allows for meaningful comparisons. A $10 increase might be significant for an item costing $20 (a 50% increase), but negligible for an item costing $1,000 (a 1% increase). It helps in:
- Financial Analysis: Tracking stock performance, investment returns, and budget variances.
- Economic Reporting: Measuring inflation, GDP growth, and unemployment rates.
- Scientific Research: Analyzing experimental results and changes in measurements.
- Business Metrics: Evaluating sales growth, customer retention, and operational efficiency.
Using the Calculator
Our Percentage Change Calculator simplifies this process. Simply enter your "Original Value" and "New Value" into the respective fields, click "Calculate Percentage Change," and the tool will instantly provide you with the percentage increase or decrease. This eliminates manual calculations and reduces the chance of errors, making it a quick and reliable way to get your results.