Financial Tool

Percentage Change Calculator

Calculate the percent increase or decrease between two numbers. Ideal for tracking stock prices, weight loss, or business growth.

Original Value (From)

New Value (To)

Σ The Formula

% Change = ((New Value - Old Value) / |Old Value|) × 100

Real World Examples

Stock Market Gain

Price from $50 to $75: ((75-50)/50) × 100 = +50% increase

Weight Loss Goal

Weight from 200 lbs to 180 lbs: ((180-200)/200) × 100 = -10% decrease

Revenue Growth

Sales from $100k to $150k: ((150-100)/100) × 100 = +50% growth

Population Decline

City from 5000 to 4500 people: ((4500-5000)/5000) × 100 = -10% decline

# About This Calculator

The Percentage Change Calculator is a powerful tool designed to quantify the difference between an initial value and a final value. It expresses this difference as a percentage, providing a standardized way to measure growth, decline, or deviation. Whether you are analyzing stock market trends, tracking personal fitness goals, or evaluating business performance, understanding percentage change gives you actionable insights that raw numbers alone cannot provide.

Understanding Percentage Change

Percentage Increase (+)

Occurs when the final value is greater than the initial value. This typically represents growth, profit, or inflation.
Example: Initial $100 → Final $120 = 20% Increase.

Percentage Decrease (-)

Occurs when the final value is less than the initial value. This represents loss, discount, or reduction.
Example: Initial $100 → Final $80 = 20% Decrease.

The Formula

The calculation is derived from the difference between the two values relative to the starting value:

Percentage Change = ((V_new - V_old) / |V_old|) × 100

Note: The absolute value of the denominator ensures the direction of change remains correct even if starting with negative numbers (e.g., debt reduction).

Real-World Applications

Finance & Investing

Investors use this to track ROI (Return on Investment), analyzing how much a stock or portfolio has grown over time.

Economics

Economists track inflation (CPI), GDP growth, and employment rates using percentage change to understand the health of an economy.

Explore Related Comparison Tools

If you are analyzing data differences, check out these related calculators:

Percentage Calculator - Find X% of a number.
Percentage Difference - Compare two values without a specific "start" or "end".
Percentage Error - Compare an experimental value to a known true value.

How To Use

Enter the Original Value (the starting number).
Enter the New Value (the ending number).
Click Calculate Change to see the percentage increase or decrease.

Frequently Asked Questions

Can percentage change be negative?+

Yes! A negative percentage change indicates a decrease. For example, if sales drop from 100 to 80 units, the result is -20%, meaning a 20% decrease.

What happens if the starting value is zero?+

Mathematically, percentage change from zero is undefined because you cannot divide by zero. Any increase from zero is technically an infinite percentage growth. In business reporting, this is often marked as 'N/A' or shown as absolute growth instead.

How is Percentage Change different from Percentage Difference?+

Percentage Change has a specific direction (Old to New). Percentage Difference compares two values without implying one came first (e.g., comparing the height of two buildings).

How do I calculate percentage change with negative numbers?+

The formula uses the absolute value of the original number in the denominator: ((New - Old) / |Old|) * 100. This ensures that if you go from -10 to -5 (an improvement), the result is positive (+50%).

What is a 'percentage point' difference?+

Percentage points refer to the arithmetic difference between two percentages. If interest rates go from 4% to 5%, that is a 1 percentage point increase, but a 25% percentage change increase.

Why doesn't a 50% increase followed by a 50% decrease act as a wash?+

Because the base changes. $100 + 50% = $150. Then $150 - 50% = $75. You end up with less than you started! Losses hurt more than equivalent gains help mathematically.