Percentage Calculator
Online percentage calculator: what percent is X of Y, percent increase/decrease, etc.
How it works
Percentage = (X ÷ Y) × 100%
A percentage shows how many parts per hundred one number is of another. The common question "what percent is X of Y" uses (X ÷ Y) × 100%.
Percent change measures the relative change from an old value to a new value: ((new − old) ÷ old) × 100%. Positive means increase, negative means decrease.
FAQ
What is the difference between percent and percentage point?
Percent is a relative ratio (e.g. 20%); a percentage point is an absolute unit of difference (e.g. a rise from 20% to 25% is +5 percentage points).
Worked example
15% of 80: 80 × 0.15 = 12.
80 as a percentage of 200: 80 ÷ 200 × 100% = 40%.
If 15% of a number is 12, the number is 12 ÷ 0.15 = 80.
Notes and limitations
Before any percentage calculation, ask: "what is the denominator?" Discounts, raises, tax rates and growth rates all use different bases. Writing the base down prevents most errors.