How to Calculate Percentage Change
Percentage change shows how much a value has increased or decreased compared with its starting value. It is useful for comparing prices, measurements, scores, and other quantities over time.
The percentage-change formula
A positive result means the value increased. A negative result means the value decreased. The original value must not be zero, because division by zero is undefined.
Example 1: Calculate a percentage increase
A subscription price rises from 40 to 50.
- Subtract the original value: 50 − 40 = 10.
- Divide by the original value: 10 ÷ 40 = 0.25.
- Multiply by 100: 0.25 × 100 = 25%.
The price increased by 25%.
Example 2: Calculate a percentage decrease
A product price falls from 80 to 60.
- Find the change: 60 − 80 = −20.
- Divide by the original value: −20 ÷ 80 = −0.25.
- Multiply by 100: −0.25 × 100 = −25%.
The result is −25%, meaning the value decreased by 25%.
Percentage change versus percentage difference
Percentage change uses a specific starting value as the baseline. Percentage difference is a different comparison that commonly relates the absolute difference to the average of the two values. Choose the method that matches the question being asked.
Common mistakes
- Dividing by the new value instead of the original value.
- Forgetting to multiply the decimal result by 100.
- Ignoring the negative sign when a value decreases.
- Using percentage change when the original value is zero.
Calculate it with a tool
For another calculation, open the HandyTools Percentage Calculator and enter the values required by the tool. Check whether you need a basic percentage, a percentage increase/decrease, or a different percentage operation.
Frequently asked question
Can percentage change be greater than 100%?
Yes. If a positive original value grows by more than its original amount, the percentage increase exceeds 100%. For example, a value increasing from 20 to 50 rises by 150%.