Measuring how much something changed
Percentage change shows how much a value has risen or fallen relative to where it started. It is the language of price rises, pay increases, investment returns, and statistics in the news, because it puts change in context — a $10 increase means one thing on a $20 item and something very different on a $2,000 one.
How to use the calculator
Enter the original value and the new value. The calculator returns the percentage change and tells you whether it is an increase or a decrease. A positive result is growth; a negative result is a reduction.
The formula
Percentage change = (New − Old) ÷ Old × 100. A price moving from $200 to $250 is (250 − 200) ÷ 200 × 100 = +25%. Moving back from $250 to $200 is −20% — notice the two percentages are not equal, because the starting point (the denominator) is different each time.
Percentage points versus percentage change
This is a subtle but important distinction. If an interest rate rises from 5% to 6%, that is a 1 percentage-point increase, but a 20% relative increase (1 is 20% of 5). News reports often blur the two, so knowing the difference helps you read economic figures accurately. Use percentage change whenever you want to describe the size of a move relative to its starting value.