Starting and ending values remain in your browser. The percentage change and numeric difference are calculated locally without an account or uploaded data.
How to Use the Percentage Change Calculator
- Enter the starting or original value.
- Enter the ending or new value.
- Read the signed percentage change and whether it is an increase, decrease, or no change.
- Use the numeric difference and substituted formula to check the result.
How Percentage Change Works
Subtract the starting value from the ending value, divide that difference by the absolute starting value, and multiply by 100. A positive result means the ending value is higher. A negative result means it is lower. This tool uses the absolute starting value in the denominator so the sign consistently follows the direction of the numeric change, including when the starting value is negative.
Formula: percentage change = (ending value - starting value) / |starting value| x 100. Numeric change = ending value - starting value.
Percentage Change Examples
Increase from 50 to 65
The numeric increase is 15. Divide 15 by the starting value of 50 and multiply by 100. The percentage change is +30%.
Decrease from 80 to 60
The numeric change is -20. Divide -20 by 80 and multiply by 100. The percentage change is -25%.
Why Reversing a Change Gives a Different Percentage
An increase from 100 to 120 is +20%, but a decrease from 120 back to 100 is about -16.67%. The amount changes by 20 both ways, but the starting denominator is different. Percentage increases and decreases are therefore not automatically symmetrical.
Percentage Change from Zero
A starting value of zero makes ordinary percentage change undefined because the formula would divide by zero. The calculator reports that limitation while still showing the numeric difference and direction. Phrases such as an infinite percent increase are sometimes used informally, but they are not a finite percentage-change result.
Percentage Change vs. Percentage-Point Change
Percentage change compares values relative to the starting value. Percentage-point change subtracts two percentages directly. If a rate rises from 20% to 25%, the change is 5 percentage points, while the relative percentage increase is 25%.
Negative Starting Values
Different fields use different conventions for changes involving negative values. This calculator divides by the absolute starting value, so moving from -100 to -50 is shown as a 50% increase because the ending value is numerically higher. When a report or domain specifies another convention, follow that definition.