Percentage Change Calculator
Compute ((B − A) ÷ |A|) × 100 to measure relative change from A to B.
Calculator
Use the Percentage Change Calculator
Result
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Formula
((B − A) ÷ |A|) × 100
Step-by-step
- 1
Enter the old value
This is your starting point A.
- 2
Enter the new value
This is your ending point B.
Worked example
Example input: a: 100, b: 120
Result: 20
Related tools
- Percentage Increase
Raise a value by a percentage.
- Reverse Percentage
Find the original whole.
Frequently asked questions
How is percentage change computed?
New minus old, divided by the absolute old value, times 100: moving from 100 to 120 is +20 percent. The calculator shows the signed number, so direction is built in.
How do I read an increase versus a decrease?
The sign says it: positive output marks growth from A to B, negative marks a fall. From 120 back to 100 the same pair reads -16.7 percent, because the base has changed to 120.
Why does a starting value of zero fail?
Percent change is relative, and no relative statement exists against an absolute zero base — dividing by it is undefined. Run the comparison from any nonzero starting point instead.