Percentage Calculator
Fast, versatile online percentage calculator with real-time results and step-by-step mathematical formulas.
1. Calculate Percentage of a Value
Find the exact value of a given percentage (e.g., What is 15% of 240?).
How to Calculate Percentages (Formulas & Guides)
A percentage represents a ratio or fraction expressed as parts per hundred (from the Latin per centum). It provides a standardized way to compare proportions, measure changes, and evaluate relative performance across mathematics, web development, finance, and marketing.
1. Percentage of a Number Formula
To find P% of X: convert the percentage into a decimal by dividing by 100, then multiply by the total value.
2. What Percentage X is of Y
To find what portion part X represents of whole Y: divide X by Y and multiply by 100.
3. Percentage Increase and Decrease Formula
When comparing changes over time (such as monthly traffic growth or revenue shifts):
4. Percentage Difference vs Percentage Change
Percentage Change implies direction and time: there is an old value and a new value. Percentage Difference is used when comparing two numbers where neither has priority (for example, comparing the prices of two competing products). The denominator used is the average of the two numbers:
Practical Use Cases for Developers & Marketers
Marketing CTR & Conversions
Calculate Click-Through Rates (Clicks ÷ Impressions × 100) or Conversion Rates (Conversions ÷ Visitors × 100) to measure marketing campaign efficiency.
E-commerce Discounts & Margins
Quickly compute promotional discounts, gross margins, and sales tax additions for store catalogs, shopping cart logic, or invoice generation.
A/B Test Lift & Growth
Measure relative test lift between variant B and control A to confirm statistical significance and overall product growth metrics.
Frequently Asked Questions
How do I calculate what percentage X is of Y?
Divide X by Y, then multiply the result by 100. For example, to find what percentage 25 is of 200: (25 ÷ 200) × 100 = 12.5%.
How do I calculate percentage increase or decrease?
Subtract the original value from the new value, divide by the absolute value of the original, then multiply by 100. Formula: ((New - Old) ÷ |Old|) × 100. A positive result indicates an increase, while a negative result represents a decrease.
What is the difference between percentage change and percentage difference?
Percentage change compares an old value to a new value over time or sequence (using the initial value as the denominator). Percentage difference compares two concurrent values where neither is considered the "original" (using the average of the two numbers as the denominator).
How do I calculate discounts and sales tax?
To apply a discount, multiply the original price by the discount percentage divided by 100, then subtract that amount. For sales tax, multiply the price by the tax rate divided by 100, then add that amount to the base price.
Is this percentage calculator free to use?
Yes. This tool is 100% free with no registration or limits. All calculations are executed directly in your browser with instant visual feedback and step-by-step formula breakdowns.