Percentage change tells you how much a value has grown or shrunk relative to where it started. It is the standard way to describe price rises, salary increases, population growth or a drop in sales.
Formula
Percentage change = (New − Original) ÷ |Original| × 100
A positive result is an increase and a negative result is a decrease.
Percentage difference is different: it divides by the average of the two values, so the order of the numbers does not matter.
Worked example
A price goes from $80 to $100. The change is 100 − 80 = 20, and 20 ÷ 80 × 100 = 25%. The price increased by 25%.
Why increases and decreases are not symmetric
Going from 80 to 100 is a 25% increase, but going from 100 back to 80 is only a 20% decrease, because the starting value is different each time.
Frequently asked questions
How do I calculate percent increase?
Subtract the original value from the new value, divide by the original value, and multiply by 100.
What is the difference between percentage change and percentage difference?
Percentage change measures growth from a starting value. Percentage difference compares two values with no starting point, dividing by their average.
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