Percent Change Calculator

Percentage increase or decrease between two values, percent difference, or a value after a % change.

Percent change = (new − original) ÷ |original| × 100. Going from 80 to 60 is a 25% decrease; from 60 to 80 is a 33.3% increase. Percent difference uses the average of the two values as the base instead.

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How to use it

Choose percent change, percent difference, or apply a percentage.
Enter the original and new values (or a value and a percentage).
Read the percentage increase or decrease and the change.

What you enter

Original value
New value

What you get

Percent increase or decrease
Absolute change
Percent difference

Formula

% change = (new − old) ÷ |old| × 100 | % difference = |a − b| ÷ ((a + b) ÷ 2) × 100

Worked example

Input: Original 80, new 60

Result: 25% decrease (−20)

The drop is measured against the starting value of 80.

Questions

How do you calculate percentage decrease?

Subtract the new value from the original, divide by the original, and multiply by 100. From 80 to 60: (80 − 60) ÷ 80 × 100 = 25% decrease.

Why is a 25% decrease not undone by a 25% increase?

The base changes. 80 down 25% is 60, but 60 up 25% is only 75. You need a 33.3% increase to get back to 80.

What is the difference between percent change and percent difference?

Percent change has a direction and uses the original value as the base. Percent difference compares two values with no starting point, using their average as the base.

Can percent change be more than 100%?

Yes for increases: going from 50 to 150 is a 200% increase. A decrease cannot exceed 100% unless the value turns negative.

Limitations

Percent change is undefined when the original value is zero.

References

OpenStax, Introductory Statistics 2e, Rice University.

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All free tools · By Dr. Zubair Khalid, DVM, MS, PhD.