How to use
Pick one of three modes:
- % of — Find
X%of a number (e.g. 15% of 200 = 30). - % change — Compute the percent change from one value to another.
- is what % — Find what percentage the first number is of the second.
Formula & theory
% of: result = (percent / 100) × value
% change: result = (to − from) / from × 100%
is what %: result = part / whole × 100%
Common pitfalls
- A 50% increase followed by a 50% decrease does not return to the original value (1 × 1.5 × 0.5 = 0.75).
- Don't average percentages without weighting — average the underlying counts instead.