Choose the right percentage operation
To find 15% of 250, choose Percent of a number and enter 15 for A and 250 for B. To find what percent 30 is of 120, choose What percent is A of B; the result is 25%.
For percentage change, A is the original value and B is the new value. Changing 200 to 250 gives a 25% increase. The original value cannot be zero. A symmetric percentage difference is a different calculation; use the separate percentage difference tool for that task.
What is this calculator?
Find a percentage of a number, one value as a percent of another, or percentage change.
What can you use it for?
Use it when solving an exercise, checking a result, or working with the particular quantities shown in this form. Find a percentage of a number, one value as a percent of another, or percentage change.
How to use it
- Enter calculation.
- Enter a / percent / original value.
- Enter b / number / new value.
- Select Calculate (or Generate for random tools).
- Read the answer and any additional results below the form. Check the units and the limits of the method.
Formula and method
A as a percent of B = A ÷ B × 100
Change = (new − original) ÷ |original| × 100
Choose the relevant operation first. A zero denominator cannot produce a defined percentage.
Worked example
Calculation: Percent of a number, A / percent / original value: 15, B / number / new value: 2500. The result is 375 (15% of 2,500).
Assumptions and limits
Inputs and outputs must stay within the supported finite number range. Displayed decimal answers may be rounded.
Frequently asked questions
How is percentage change calculated?
Percentage change is (new value minus original value) divided by the absolute original value, multiplied by 100. The original value must not be zero.
How do I calculate 15% of 250?
Choose the percent-of-value operation and enter 15 and 250. The answer is 37.5 because 15 ÷ 100 × 250 = 37.5.
What inputs does the Percentage Calculator need?
Use calculation, a / percent / original value, b / number / new value. Read the answer and any additional results below the form. Check the units and the limits of the method.
What assumptions apply to the Percentage Calculator?
Inputs and outputs must stay within the supported finite number range. Displayed decimal answers may be rounded.