Percentage Increase/Decrease Calculator
Percentage change tells you how much a value has grown or shrunk relative to where it started. It is the basis for reporting price rises, salary changes, population shifts and almost any before-and-after comparison. This calculator takes an original value and a new value, then shows the percentage change, whether it is an increase or a decrease, and the absolute difference. Enter both numbers to see the result instantly.
Percentage change formula
difference = new value - old value
percentage change = (difference / old value) * 100
positive result = increase, negative result = decrease
The percentage is always relative to the original value, which acts as the reference. The sign of the result tells you the direction: positive means the value rose, negative means it fell.
Worked example
A product's price rises from 200 to 250. The difference is 250 - 200 = 50. The percentage change is (50 / 200) times 100 = 25.00 percent. Because the result is positive, this is a 25 percent increase, with an absolute difference of 50.00.
Percentage change: frequently asked questions
How do you calculate percentage increase or decrease?
Subtract the original value from the new value, divide by the original value, and multiply by 100. The formula is ((new - old) / old) times 100. A positive result is a percentage increase, a negative result is a percentage decrease. For example, going from 200 to 250 is ((250 - 200) / 200) times 100 = 25 percent increase.
What is the difference between a percentage increase and a percentage point change?
A percentage increase compares the change relative to the starting value. A percentage point change is the simple arithmetic difference between two percentages. If an interest rate rises from 4 percent to 5 percent, that is a 1 percentage point increase but a 25 percent increase (because 1 divided by 4 is 0.25). The two are easily confused, so it is important to state which you mean.
Why can a percentage decrease never exceed 100 percent?
A decrease of 100 percent means the value has fallen to zero. You cannot lose more than everything you started with, so a percentage decrease relative to a positive starting value is capped at 100 percent. A percentage increase, by contrast, has no upper limit: a value can grow to many times its original size.
Why is the original value the denominator and not the new value?
Percentage change measures growth or shrinkage relative to where you started, so the original value is the reference point and goes in the denominator. Using the new value as the denominator would answer a different question and gives an asymmetric result. A rise from 100 to 150 is a 50 percent increase, but a fall from 150 back to 100 is only a 33.33 percent decrease, because the reference value differs.
Official sources
- U.S. Bureau of Labor Statistics: Consumer Price Index (percentage change methodology).
- National Institute of Standards and Technology: Guide for the Use of the International System of Units (SI).
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.