Percentage Change Calculator

How to use the percentage Change Calculator

1. Enter the original value.
2. Enter the new value.
3. The result updates instantly as you type. There is no button to press.
4. Use Copy result to copy the figures, or Copy link to share a link that reopens the percentage Change Calculator with the same inputs.

How it works

Percentage change describes how much something grew or shrank relative to where it started. It is how we compare price rises, sales growth, population change, test scores and investment returns, because it puts changes of different sizes on the same scale. A rise from 50 to 75 and a rise from 500 to 750 are both 50% increases.

The key is always to divide by the original value. That is why percentage changes are not symmetric: going from 50 to 75 is a 50% increase, but going back from 75 to 50 is only a 33.3% decrease. The calculator shows both directions so you can see the difference.

It also shows the percentage difference, which compares two values without treating either as the starting point. It divides the gap by the average of the two, which suits comparing two measurements, two shops' prices or two experimental results where neither is "before". When the original value is negative, the calculator divides by its absolute value, so a move from −10 to −5 is reported as a 50% increase.

Formula

A positive result is an increase and a negative result a decrease. A multiplier of 1.5 means the new value is one and a half times the old.

Example

A price rises from $50 to $75. The change is +25, and 25 ÷ 50 × 100 = a 50% increase; the multiplier is 1.5. If it then falls back to $50, that is a 25 ÷ 75 = 33.33% decrease. The percentage difference between 50 and 75 is 25 ÷ 62.5 × 100 = 40%, the same whichever way round you put them.

Frequently asked questions