Percentage Change Calculator
Calculate the percentage change between two values. Determines whether there was an increase or decrease and by what percentage, perfect for tracking price changes, performance metrics, and trends.
This free online percentage change calculator provides instant results with no signup required. All calculations run directly in your browser — your data is never sent to a server. Enter your values below and see results update in real time as you type. Perfect for everyday calculations, homework, or professional use.
The initial or starting value
The final or ending value
Results
Absolute Change
50
Percentage Change
25%
How to Use This Calculator
Enter your input values
Fill in all required input fields for the Percentage Change Calculator. Most fields include unit selectors so you can work in your preferred unit system — metric or imperial, whichever matches your problem.
Review your inputs
Double-check that all values are correct and that you have selected the right units for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.
Read the results
The Percentage Change Calculator instantly computes the output and displays results with units clearly labeled. All calculations happen in your browser — no loading time and no data sent to a server.
Explore parameter sensitivity
Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.
Formula Reference
Percentage Change Calculator Formula
See calculator inputs for the governing equation
Variables: All variables and their units are labeled in the calculator interface above. Input fields accept values in multiple unit systems — select your preferred unit from the dropdown next to each field.
When to Use This Calculator
- •Use the Percentage Change Calculator when you need a quick mathematical result without writing out all the steps manually, saving time on repetitive calculations.
- •Use it to verify hand calculations on tests or assignments and catch arithmetic mistakes.
- •Use it when teaching or explaining mathematical concepts to others, demonstrating how changing inputs affects the result.
- •Use it to explore the behavior of mathematical functions across a range of inputs.
About This Calculator
The Percentage Change Calculator is a free mathematical calculation tool for students, educators, and professionals who need quick, reliable results. Calculate the percentage change between two values. Determines whether there was an increase or decrease and by what percentage, perfect for tracking price changes, performance metrics, and trends. The underlying algorithms implement well-established mathematical formulas and numerical methods. Results are computed instantly in the browser. This tool is useful for learning, verification of hand calculations, and rapid exploration of mathematical relationships. All computation happens locally — no data is sent to a server.
About Percentage Change Calculator
The Percentage Change Calculator computes how much a value has increased or decreased relative to its original amount, expressed as a percentage. A positive result indicates an increase, while a negative result indicates a decrease. This calculation is one of the most widely used in data analysis, finance, economics, and everyday life. Whether you are tracking how much a stock price has moved, comparing this month's sales to last month's, or measuring a change in temperature, percentage change gives you a standardized way to describe the magnitude of the shift. Unlike absolute change, which depends on the units involved, percentage change is dimensionless and allows meaningful comparisons across different scales.
The Math Behind It
Formula Reference
Percentage Change
((New - Old) / |Old|) * 100
Variables: New = new value, Old = original value
Worked Examples
Example 1: Stock Price Change
A stock goes from $200 to $250.
The stock price increased by 25%.
Example 2: Temperature Drop
The temperature falls from 80°F to 68°F.
The temperature decreased by 15%.
Example 3: Revenue Decline
Monthly revenue drops from $50,000 to $42,000.
Revenue declined by 16%.
Common Mistakes & Tips
- !Using the new value instead of the old value as the denominator. The denominator must be the original (starting) value.
- !Forgetting that a 50% increase followed by a 50% decrease does not return to the starting value.
- !Attempting to calculate percentage change from a starting value of zero, which is undefined.
- !Confusing percentage change with percentage point change. A move from 10% to 15% is a 5 percentage point increase, but a 50% percentage change.
Related Concepts
Used in These Calculators
Calculators that build on or apply the concepts from this page:
Frequently Asked Questions
What if the old value is negative?
The calculator uses the absolute value of the old value in the denominator, so it handles negative starting values correctly. A change from -20 to -10 is a +50% change.
Is percentage change the same as percentage difference?
No. Percentage change is directional (old to new), while percentage difference uses the average of the two values as the base. Use percentage change when you have a clear before-and-after relationship.
Can percentage change be greater than 100%?
Yes. If the new value is more than double the old value, the percentage change exceeds 100%. For example, going from 50 to 150 is a 200% increase.