The formula
Subtract the original value from the new value, divide by the size of the original value, then multiply by 100.
A positive answer is an increase and a negative answer is a decrease. The calculator shows the sign, so you can see the direction.
Worked example
A value goes from 150 to 180. The change is 30, and 30 / 150 x 100 = 20%, so the value rose by 20%.
Going the other way, from 180 down to 150, is 30 / 180 x 100 = 16.6667%, a smaller percentage fall because the base is larger.
Change, difference and percentage points
Percentage change compares a change with the starting value. Percentage difference compares two values with their average, which suits neither being the starting point.
A rate moving from 4% to 5% has risen by 1 percentage point but by 25% in relative terms. Say which one you mean.
Inputs for the percentage change calculator
Original value
The value you start from. It becomes the base of the comparison, so it cannot be zero.
New value
The value after the change. It can be higher or lower than the original.
CALCULATOR QUESTIONS
Percentage change calculator questions
How do I work out the percentage change?
Divide the change by the original value and multiply by 100. From 150 to 180, the change is 30 and 30 / 150 x 100 = 20%.
What if the new value is lower?
The answer is negative. From 180 to 150 the change is -30 and the percentage change is -16.6667%.
Why can't the original value be zero?
The change is divided by the original value, and division by zero has no answer.
Is percentage change the same as percentage difference?
No. Percentage change divides by the original value. Percentage difference divides by the average of the two values.