Finance & Business
Percentage, Ratio & Proportion Calculator
Six everyday percent and ratio problems, one tool: percent of a number, reverse percentages, percentage change, ratio simplification, and proportions.
Formula
Six relationships, one idea
Percent = Part ÷ Whole × 100
X% of YY \u00d7 (X / 100)
X is what % of Y(X / Y) \u00d7 100
% change((To \u2212 From) / From) \u00d7 100
Reverse %X / (N / 100)
Ratio A:BDivide both sides by their greatest common divisor
Proportion A:B = C:xx = (B \u00d7 C) / A
FAQ
Common questions
Percentage change is always relative to its own starting point. Dropping 100 by 20% gives 80. Increasing 80 by 20% only adds 16, landing at 96 — not back at 100 — because the second 20% is measured against the smaller number. The "% change" mode above always reports the change relative to the "From" value for this reason.