How this calculation works
Choose the question before entering A and B: the same two numbers can describe a percentage, a part or an unknown whole. This tool solves one part–whole relationship. Use percentage change for a before-and-after comparison, or percentage difference when neither value is the baseline.
Worked example
This example uses illustrative inputs. Your current result is shown above.
Choose “What is A% of B?”, enter A = 25 and B = 200: 25 × 200 ÷ 100 = 50. The result is an amount, not 50%.
Assumptions and limits
- In “A is what percent of B?”, B is the nonzero reference whole.
- Finding an unknown whole requires a nonzero A. Use matching units when A and B represent amounts.
- Negative values are allowed for signed arithmetic; they do not necessarily describe a share of a physical whole.
Questions people ask
Why do the three modes give different answers?
They solve for different unknowns. “Percent of” finds an amount, “what percent” finds a percentage, and “percent of what” finds the original whole. Read the selected sentence with your values substituted.
Is a change from 20% to 25% a 5% increase?
It is an increase of 5 percentage points. Relative to 20%, the increase is 25%. Use the percentage-change calculator to distinguish those two quantities.