Percent of a value
Input: 18% of 2,500
Output: 450
(18 / 100) x 2500 = 450.
Percentage calculator
This page supports three common percentage calculations in one place.
What is X% of Y?
Result:
What percent is A of B?
Result:
Percent change from old to new
Result:
Formula and algorithm
- Percent of value: result = (percent / 100) x value
- What percent: percent = (part / whole) x 100
- Percent change: ((new - old) / old) x 100
Worked examples
What percent is 45 of 180
Input: Part 45, whole 180
Output: 25%
(45 / 180) x 100 = 25.
Percent increase
Input: From 80 to 100
Output: 25% increase
((100 - 80) / 80) x 100 = 25.
FAQ
What happens when whole value is zero?
The result is undefined due to division by zero, and the tool reports that clearly.
Can this show percent decrease?
Yes. If the new value is lower than old value, the change is negative.
Do I need to type the percent sign?
No. Enter numeric values only, for example 18 for 18%.
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Updated: June 7, 2026