Percentage Calculator

About Percentage Calculator

A percentage is a way to express a number as a fraction of 100. It is often denoted using the percent sign "%". Percentages are used to express proportions, rates, and comparisons between quantities.

Percentage Calculation Formulas

This calculator provides three main percentage calculations:

1. Percentage of a Number

To find what is X% of Y:

Formula: (X / 100) × Y

Example: What is 15% of 200?
(15 / 100) × 200 = 0.15 × 200 = 30

2. Percentage Increase/Decrease

To find the percentage increase or decrease from X to Y:

Formula: ((Y - X) / X) × 100

Example: What is the percentage increase from 100 to 150?
((150 - 100) / 100) × 100 = (50 / 100) × 100 = 50% increase

3. Percentage Difference

To find the percentage difference between two numbers X and Y:

Formula: (|X - Y| / ((X + Y)/2)) × 100

Example: What is the percentage difference between 100 and 150?
(|100 - 150| / ((100 + 150)/2)) × 100 = (50 / 125) × 100 = 40% difference

Common Percentage Applications

• Discounts: Calculating sale prices (e.g., 20% off $50)
• Tips: Calculating restaurant tips (e.g., 15% of the bill)
• Interest Rates: Calculating loan interest or investment returns
• Statistics: Expressing proportions in surveys or research
• Growth Rates: Measuring business or population growth

Tips for Percentage Calculations

• Remember that 100% represents the whole amount
• To find 10% of a number, simply move the decimal point one place to the left
• To increase a number by a percentage, multiply by (1 + percentage/100)
• To decrease a number by a percentage, multiply by (1 - percentage/100)
• When comparing percentages, always consider the base amounts