Choose the question you want to answer
- Select an operation; the input labels change to match it.
- Enter the two values and calculate.
- Copy or download the result. Editing either value clears the previous answer.
Formulas and examples
Percentage of a number: percentage ÷ 100 × number. For example, 20% of 150 is 30. Part as a percentage of a whole: part ÷ whole × 100. For example, 42 of 50 is 84%.
Percentage change: (new − original) ÷ original × 100. From 2,500 to 2,425 is −3%, a decrease. The original value must be positive in this tool. A zero original does not define a percentage change, and negative originals require a different interpretation.
Microsoft’s percentage examples document part/whole and change formulas. The same arithmetic can be useful for everyday quantities, finance or education; this is one shared tool.
Limits and interpretation
Inputs must be finite and between −1 trillion and 1 trillion. Whole magnitude must be at least 0.000000000001 for ratios; a change’s original must be at least that positive value. Signed percentages and ratios, and percentages above 100, are permitted. This tool does not impose marks, tax, discount or grading rules.
Results use floating-point arithmetic, displayed with up to six decimals or scientific notation for very small/large values. Rounding can hide differences beyond display precision. Currency, interest compounding and percentage-point comparisons are not calculated. This is arithmetic, not financial advice or a policy verdict.
Privacy
Values stay in browser memory with no upload or saved inputs. CSV includes the operation, input values and numeric answer; the unit column distinguishes a percentage from a number. Reset restores the default operation and values. Switching questions loads that question’s worked example. Undo last action restores your previous operation, raw inputs and accepted result after a mode change, example or Reset. Editing a value discards that recovery step.
Is percentage change the same as percentage points?
No. A rate rising from 10% to 12% increases by 2 percentage points and by 20% relative to the original rate. Enter 10 and 12 in change mode for that 20% calculation.
Can the answer exceed 100%?
Yes. A part can exceed the chosen whole, or a value can more than double. The formula does not cap the result.