Percent Change Calculator

This calculator finds the percentage increase or decrease between an old value and a new value. It also shows the absolute difference, so you can see both the size and the direction of the change.

Old value

New value

Enter both values.

How to use it

Enter the starting value in the first box and the final value in the second. The result shows whether the value rose or fell and by what percentage. Negative numbers are allowed.

How it is calculated

Percent change = (new - old) / |old| x 100. A positive result is an increase, a negative one is a decrease. The absolute value of the old number in the denominator keeps the sign meaningful when the starting value is negative.

The change is undefined when the old value is zero, so the tool shows a message instead of a number.

Examples

From 80 to 100: (100 - 80) / 80 x 100 = 25 percent increase.

From 100 to 80: (80 - 100) / 100 x 100 = -20 percent, a 20 percent decrease. Note that going up 25 percent and then down 20 percent returns to the start, which is why the two directions give different percentages.

Good to know

Percent change is useful for prices, salaries, website traffic, grades, savings and test results. When comparing two percentages themselves, say whether you mean points or relative change. For several periods in a row, do not add percentages together; calculate each step from its own start, or compare the first and last values directly.

FAQ

Why is the percent change different going up and down?

Each change is measured against its own starting value, so the same gap gives different percentages.

What is the difference between percent change and percentage points?

Going from 10 percent to 12 percent is 2 percentage points but a 20 percent relative increase.

What happens if the old value is zero?

Division by zero is undefined, so no percentage can be given.

Can I use negative numbers?

Yes. The formula divides by the absolute old value so the direction stays correct.