How to Calculate Percentages the Easy Way
Percentages appear everywhere: discounts, tips, grades and interest. Learn the simple methods to calculate any percentage by hand or instantly with a free tool.
Percentages are one of the most useful everyday maths skills, from working out a sale price to checking a tip or an exam score. Once you know a few basics, they become easy.
The core idea
Percent means per hundred. So 20% is simply 20 out of 100, or 0.20. To find a percentage of a number, multiply: 20% of 150 is 30.

Three common questions
- What is X% of Y? Multiply Y by X/100.
- X is what percent of Y? Divide X by Y, then multiply by 100.
- Percentage change? (new - old) divided by old, then multiply by 100.
Skip the mental maths
For quick, error-free answers, use the free Percentage Calculator. It handles percent of, what percent, and percentage increase or decrease in one place.
Where you will use this
Percentages show up in discounts, taxes, tips, test scores, and loan interest. If you are planning a loan, see how percentages drive your repayments in how loan EMI works.