Calculators
Percentage calculator
Calculate percentages, percentage change, and increases or decreases.
Calculation
No thousands separators. Numbers: up to 1e100; nonzero magnitudes at least 1e-100. Results rounded to 12 significant digits.
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How to use this calculator
- Choose the calculation and input format.
- Enter your values or load the worked example.
- Read the result, then copy or download it as text.
Calculation rules
For “percentage of”, the formula is percentage ÷ 100 × number. A 15% share of 200 is 30. To find a percentage, divide the part by the whole and multiply by 100. A zero whole has no valid percentage result.
Questions and answers
How does percentage change differ from a percentage of a number?
Percentage change is (new − original) ÷ original × 100. The original must be positive. Going from 80 to 100 gives +25%; the reverse gives −20%. For adjustments, start with a nonnegative amount and percentage; a decrease greater than 100% can produce a negative result.