How to use this tool
Choose the percentage question you need to answer before entering the two values.
For percentage change, enter the positive original value first and the new value second. A decrease is shown as a negative change.
Part = percentage ÷ 100 × whole; change = (new − original) ÷ original × 100
Worked example
30 · result
Fixed example using the settings below. Monetary examples use USD; dates and times use their stated reference values. This example stays unchanged when you edit your calculation.
Example inputs
- Calculation: What is A% of B?
- Percentage (%): 20
- Whole amount: 150
Method illustration: 20% of 150 is 30. A change from 100 to 120 is a 20% increase.
Assumptions and limits
- Percentage change uses A as the original value and B as the new value. The original value must be positive for this comparison.
- A zero whole or zero reverse percentage cannot be used as a denominator. Percentages above 100 are allowed.
Check or report a result
Check the units, selected calculation and assumptions first. Compare the fixed example above with your inputs to identify what changed.
Report a calculation issue with the page address, hypothetical inputs, result displayed and result expected. Do not include passwords, bank details or other private information.