Percentage Calculator
Instantly perform three common percentage calculations: find the percentage of a number, determine one number's percentage of another, or find the original number.
Calculate a Percentage of a Number
This is the most common percentage problem, often used for discounts or tips. Use this to find out what a certain percentage of a number is.
Determine a Percentage
Use this to find what percentage one number is of another. Useful for calculating test scores or sales tax rates.
Find the Original Number
This calculation helps you find the original number when you know a portion of it and the percentage that portion represents. This is useful for reversing a discount or a tax calculation.
About this Percentage Calculator
Percentages are a fundamental part of daily life, used in finance, shopping, and statistics. This tool provides a quick and easy way to solve the three most common types of percentage problems.
This tool is completely client-side. All calculations are performed instantly in your browser using JavaScript, so your data remains private and is never sent to a server.
How the Calculations Work
- What is A% of B?: The formula is simply $(A \div 100) \times B$. For example, to find 20% of 150, the tool calculates $(20 \div 100) \times 150 = 30$.
- A is what % of B?: To find what percentage A is of B, the formula is $(A \div B) \times 100$. For example, to find what percentage 30 is of 120, the tool calculates $(30 \div 120) \times 100 = 25\%$.
- A is B% of what?: To find the original number, the formula is $(A \div B) \times 100$. For example, if 25 is 10% of a number, the tool calculates $(25 \div 10) \times 100 = 250$.