Percentage Increase / Decrease Calculator
Calculate percentage changes, increases and decreases between numbers for free.
Use percentage change to compare an original value with a new value. A negative result means a decrease.
Enter a non-negative percentage to calculate the adjusted value.
Percentage Change Formula
Percentage change measures how much a value has increased or decreased compared with its original value.
A positive result indicates an increase. A negative result indicates a decrease. The formula is undefined when the original value is zero because division by zero is not possible.
Percentage Increase Formula
Use this formula when the new value is greater than the original value.
Percentage Decrease Formula
Use this formula when the new value is lower than the original value. The decrease is usually reported as a positive percentage.
Worked Examples
Example 1: Percentage increase
A price rises from 80 to 100.
Change = 100 − 80 = 20.
Percentage increase = (20 ÷ 80) × 100 = 25%.
Example 2: Percentage decrease
A price falls from 200 to 150.
Decrease = 200 − 150 = 50.
Percentage decrease = (50 ÷ 200) × 100 = 25%.
Example 3: Increase a number by a percentage
Increase 500 by 10%.
10% of 500 = 50. New value = 500 + 50 = 550.
Example 4: Decrease a number by a percentage
Decrease 500 by 10%.
10% of 500 = 50. New value = 500 − 50 = 450.
Frequently Asked Questions
How do I calculate percentage increase?
Subtract the original value from the new value, divide the difference by the original value, and multiply by 100. This formula applies when the original value is not zero.
How do I calculate percentage decrease?
Subtract the new value from the original value, divide by the original value, and multiply by 100. When the value has decreased, this gives the decrease as a positive percentage.
What is the difference between percentage change and percentage difference?
Percentage change compares a new value with a specified original value. Percentage difference commonly compares two values using their average as the reference. They use different formulas.
Can I calculate a negative percentage change?
Yes. If the new value is lower than the original value, the percentage change formula returns a negative result, indicating a decrease.
How do I calculate percentage change in Excel?
If the original value is in cell A1 and the new value is in B1, use =(B1-A1)/A1 and format the result as a percentage. The formula requires a non-zero original value.
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