How do I calculate a percentage of a number?

To find X% of Y, multiply Y by X/100. For example, 15% of 200 = 200 × 0.15 = 30. This calculator handles all percentage operations including finding percentages, percentage change, and percentage differences.

How do I calculate percentage increase or decrease?

Percentage change = ((New Value - Old Value) / Old Value) × 100. A positive result is an increase; negative is a decrease. For example, going from 50 to 75 is a 50% increase: ((75-50)/50) × 100 = 50%.

What is the difference between percentage change and percentage difference?

Percentage change compares a new value to an original value (has direction: increase/decrease). Percentage difference compares two values without implying which came first, using the average of both as the base.

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Percentage Calculator

Three common percentage calculations in one tool. Results update instantly as you type — no buttons needed. Everything runs locally in your browser.

What is X% of Y?

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X is what % of Y?

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Percentage change from X to Y

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How to Calculate Percentages

A percentage represents a fraction of 100. To find X% of a number, multiply the number by X
and divide by 100. For example, 15% of 200 is (200 × 15) ÷ 100 = 30. This calculation is
used everywhere — discounts, tax, tips, grades, and financial analysis.

Finding What Percent One Number Is of Another

To determine what percentage a part is of a whole, divide the part by the whole and multiply
by 100. If you scored 42 out of 50 on a test, your percentage is (42 ÷ 50) × 100 = 84%.
This is useful for grades, completion rates, market share, and any ratio comparison.

Understanding Percentage Change

Percentage change measures the relative difference between an old and new value. The formula
is ((new − old) ÷ old) × 100. A positive result indicates an increase, and a negative result
indicates a decrease. This metric is widely used in finance to track stock performance,
revenue growth, and inflation rates. Note that the original (old) value cannot be zero, since
you would be dividing by zero.

Common Percentage Formulas

X% of Y = (Y × X) / 100. Part is what % of Whole =
(Part / Whole) × 100. % Change = ((New − Old) / Old) × 100. These three
formulas cover the vast majority of everyday percentage calculations, from shopping discounts
to salary raises to data analysis.

Free Online Percentage Calculator

This percentage calculator handles all common percentage operations: find what percent one number is of another, calculate a percentage of any number, and determine percentage increase or decrease between two values. It’s useful for calculating discounts, tax amounts, grade percentages, tip amounts, and financial ratios.

Percentage Formulas Explained

The three core percentage formulas: (1) X% of Y = Y × X/100, (2) X is what % of Y = (X/Y) × 100, and (3) Percentage change = ((New – Old) / Old) × 100. Our calculator handles all three formats automatically — just enter your numbers and get instant results.

No signup required. Calculations are performed instantly in your browser.