Percentage Change Calculator
Enter an original value and a new value to calculate the absolute change and percentage increase or decrease.
Formula: ((new value − original value) ÷ original value) × 100. Percentage change is undefined when the original value is zero.
What Is Percentage Change?
Percentage change describes how much a value has increased or decreased compared with its original value. It is useful when comparing prices, monthly expenses, sales totals, website metrics, test scores and other measurements that change over time. Expressing a change as a percentage makes it easier to compare changes across values of different sizes.
For example, an increase from 100 to 125 is a change of 25 units, which represents a 25% increase relative to the original value. A decrease from 100 to 75 is a change of minus 25 units, or a 25% decrease. The calculator above performs the arithmetic and labels the direction so you can quickly interpret the result.
How to Use This Percentage Change Calculator
- Enter the original value. This is the starting amount before the change occurred.
- Enter the new value. This is the amount after the change.
- Select decimal places. Choose how many digits to show after the decimal point.
- Calculate the change. The tool displays percentage change, the absolute numerical difference and whether the value increased, decreased or stayed the same.
- Reset if needed. Restore the example values to start another calculation.
Percentage Change Formula
The standard formula is ((new value − original value) ÷ original value) × 100. First subtract the original value from the new value to find the absolute change. Then divide that difference by the original value and multiply by 100 to express it as a percentage.
Suppose a product’s price changes from 80 to 92. The difference is 12. Dividing 12 by 80 gives 0.15; multiplying by 100 gives a 15% increase. If the price instead changed from 80 to 68, the difference would be −12, producing a −15% change, which indicates a 15% decrease.
Percentage Change vs. Percentage Difference
Percentage change compares a new value against a specific starting value. Percentage difference is often used when comparing two values without treating either one as the original; one common method divides the absolute difference by the average of the two values. These measures answer different questions, so choose the method that matches your comparison.
This calculator uses the original value as the baseline. If you are comparing two measurements that have no natural starting point, the result may not be the percentage difference you need.
How to Interpret Positive and Negative Results
- Positive percentage: the new value is greater than the original value, so the result is an increase.
- Negative percentage: the new value is less than the original value, so the result is a decrease.
- Zero percent: both values are equal and there is no change.
- Original value of zero: percentage change cannot be calculated using the standard formula because division by zero is undefined.
Common Uses for Percentage Change
Shopping and prices: compare how much a price rose or fell between two dates. Budgets: measure changes in rent, bills or monthly spending. Business: compare sales, costs, revenue or conversion figures across periods. Education: review how a score changed between tests. Analytics: summarize growth or decline in visits, sign-ups or other tracked metrics. In each case, ensure the two values use the same unit and comparable measurement period.
Important Points to Remember
The result depends on which value you use as the original. Moving from 50 to 100 is a 100% increase, while moving from 100 to 50 is a 50% decrease. These percentages are not equal because the baseline changes. Also, a percentage change can be large when the starting value is small, so review the actual numerical difference alongside the percentage.
If your values represent money in different currencies, convert them to the same currency before calculating. If one value is measured in kilograms and another in pounds, convert the units first. Percentage comparisons are meaningful only when both numbers describe the same type of quantity under comparable conditions.
Frequently Asked Questions
Can percentage change be negative?
Yes. A negative result means the new value is lower than the original value.
Why can’t I calculate a percentage change from zero?
The standard formula divides by the original value. If that value is zero, the calculation involves division by zero and has no defined percentage result.
Does the calculator round the result?
Yes. Choose the decimal-place setting to control how many digits are displayed. The calculation itself uses the entered values.
Is percentage change the same as percentage points?
No. Percentage change measures relative movement. Percentage points describe the arithmetic difference between two percentages, such as moving from 20% to 25%, which is an increase of five percentage points.
Important Note
This free percentage change calculator is intended for general mathematical and educational use. Check your source data, units and baseline before using the result in reports, financial decisions or business analysis.
Related Tools
Explore these related free tools: Percentage Calculator · Compound Interest Calculator · Discount Calculator.