% Calculator

The basic percentage formula is: Percentage = (Part / Whole) x 100. For example, if you scored 45 out of 60 on a test, your percentage is (45/60) x 100 = 75%. To find what X% of Y is, use: Result = (X/100) x Y.

Percent increase measures how much a value has grown: ((New - Old) / Old) x 100. Percent decrease measures how much it has shrunk, using the same formula but resulting in a negative value. A 50% increase followed by a 50% decrease does NOT return to the original value.

Percentage points measure the arithmetic difference between two percentages. For example, going from 10% to 15% is an increase of 5 percentage points, but a 50% increase in the rate itself. This distinction matters in finance, statistics, and polling data.

Common fractions to percentages: 1/2 = 50%, 1/3 = 33.33%, 1/4 = 25%, 1/5 = 20%, 1/8 = 12.5%, 1/10 = 10%, 2/3 = 66.67%, 3/4 = 75%. To convert a decimal to a percentage, multiply by 100.

Markup is the percentage added to the cost price to get the selling price: Markup = ((Selling - Cost) / Cost) x 100. Margin is the percentage of the selling price that is profit: Margin = ((Selling - Cost) / Selling) x 100. A 100% markup equals a 50% margin.