Percentage Change Calculator
Compare an original value with a new value to calculate a directional percentage increase, decrease, or no change.
Calculate percentage change
Enter the starting value and the new value. Values must be non-negative, and the original value must be greater than zero.
Result
Compare an original value with a new value to calculate a directional percentage increase, decrease, or no change.
What is percentage change?
Percentage change measures a directional change from an original value to a new value. The original value is the reference point, so reversing the two inputs usually changes the result.
Percentage increase and decrease formula
(New − Original) ÷ Original × 100. A positive result is an increase. A negative signed result indicates a decrease; this calculator displays the magnitude together with its direction.
Worked examples
100 to 120 is a 20% increase. 100 to 75 is a 25% decrease. 100 to 100 is 0%, or no change.
Why the starting value matters
A change of 20 has different significance when starting from 100 than when starting from 200 because the starting amount defines the reference scale. An original value of zero is undefined because the formula divides by the original value.
Percentage change vs percentage difference
Percentage change is directional and uses the original value as the denominator. Percentage Difference Calculator is symmetric and compares two values relative to their average.
Frequently asked questions
Can the new value be zero?
Yes. From a positive original value, that is a 100% decrease.
Are negative values supported?
No. This version intentionally focuses on non-negative quantities.
For a basic percentage question, use the Percentage Calculator.