Percentage Calculator
What is X% of Y?
X is what percent of Y?
Percentage increase / decrease from A to B
This free Percentage Calculator solves the three percentage problems people meet most often, all on one simple page. The first tool works out what a percentage of a number is, which is what you need for discounts, tips, taxes, and exam marks. The second tool tells you what percent one number is of another, useful for scores, budgets, and comparing parts of a total. The third tool measures percentage increase or decrease between two values, which helps you understand price rises, salary changes, weight loss, business growth, and many other everyday comparisons.
Percentages look small, but a tiny mistake can change a bill, a grade, or a business decision, so doing them carefully matters. This calculator gives you a clear answer as you type, and you can also press the Calculate button for each section. There is nothing to install and no account to create. Everything runs locally in your browser, so the numbers you enter stay on your own device and are never uploaded or stored. The three sections are independent, which means you can use just one of them, or work through all three for a bigger task like checking a full shopping bill.
How to use
- Find the section that matches your question; there are three separate calculators on this page.
- Type the first number into the first box of that section.
- Type the second number into the next box, checking both values carefully.
- Read the result, which updates as you type, or click the Calculate button.
- Use a different section whenever you need another type of percentage answer.
Frequently asked questions
How do I work out a percentage of a number?
Divide the percentage by one hundred and multiply by the number. For example, twenty percent of fifty is twenty divided by one hundred, times fifty, which equals ten. The first calculator above does this for you instantly.
How is percentage increase calculated?
Subtract the old value from the new value, divide the difference by the old value, and multiply by one hundred. If a price rises from eighty to one hundred, the increase is twenty divided by eighty, which is twenty five percent.
Why does the calculator refuse division by zero?
A percentage of zero, or change from zero, has no meaningful answer in normal maths, because you cannot divide by zero. The tool shows a clear message instead of a wrong or endless result.
Can I use decimal numbers?
Yes. All boxes accept decimal values such as 12.5 or 99.99, and results are shown rounded neatly to two decimal places for easy reading.
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