Math Calculators
Percentage Change Calculator
Calculate percentage increase or decrease.
Enter the values and review the result.
The starting value or original amount.
The ending value after the change.
Calculation assumptions
- *Old value is used as the base for the percentage change.
- *Percentage change cannot be calculated when the old value is zero.
- *A positive result means increase; a negative result means decrease.
Enter your values and press Calculate.
Results and breakdowns will appear here after a valid calculation.
What percentage change means
Percentage change compares an old value to a new value. It shows how much something moved relative to where it started, which is why the old value is the base.
Percentage change formula
Use percentage change = ((new value - old value) / old value) x 100. The result is positive for an increase and negative for a decrease.
Worked examples
Increase example: Old value 100 and new value 120 gives ((120 - 100) / 100) x 100 = 20% increase.
Decrease example: Old value 200 and new value 150 gives ((150 - 200) / 200) x 100 = -25%, or a 25% decrease.
When to use percentage change
Use percentage change for price changes, sales growth, website traffic changes, salary changes, weight changes, measurements, and any situation where the starting value matters.
Common percentage change mistakes
- Using the new value as the base instead of the old value.
- Trying to calculate percentage change when the old value is zero.
- Confusing percentage change with percentage points.
- Ignoring whether the result is an increase or a decrease.
Related percentage tools
For one-way calculations, try the Percentage Increase Calculator or Percentage Decrease Calculator. You can also browse Math Calculators.
Transparency note
Accuracy and limitations
Calzivo tools are built for practical estimates, conversions, and checks. Some tools use standard formulas or simplified assumptions, and results can be affected by input accuracy, rounding, units, local rules, or changing official requirements.
Results depend on the values you enter and any simplified assumptions used by the tool. Verify important results before making decisions or submitting official information.
How to Use This Tool
Use these steps to enter the right inputs and interpret the result correctly.
Enter the original or old value.
Enter the new value after the change.
Read the percentage change and the absolute difference.
Use the sign to tell whether the change is an increase or decrease.
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Related Guides
Background reading and explanations related to Percentage Change Calculator.
Percentage Calculator Guide: What It Solves and How It Works
Learn how a percentage calculator works and what problems it solves.
How to Use a Percentage Calculator Step by Step
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Percentage Calculator Formula: Percent of, Percent Change, and Reverse Percentage
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Percentage Calculator Examples for Discounts, Scores, and Growth Rates
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Common Percentage Calculator Mistakes and How to Avoid Them
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Frequently Asked Questions
Common questions about Percentage Change Calculator and how to read the result.
How do I calculate percentage change?
Subtract the old value from the new value, divide by the old value, then multiply by 100.
What does a negative percentage change mean?
A negative result means the new value is lower than the old value, so the value decreased.
Why can't old value be zero?
The formula divides by the old value. Dividing by zero is undefined, so percentage change cannot be calculated from a zero starting point.
Is percentage change the same as percentage difference?
No. Percentage change uses the old value as the base, while percentage difference usually compares two values relative to their average.
What is the difference between percent and percentage points?
Percent describes relative change. Percentage points describe the direct difference between two percentages, such as moving from 20% to 30%.