Percentage Calculator
Three quick calculators for the percentage problems people search for most: find a percentage of a number, find what percent one number is of another, and measure percentage increase or decrease.
What is X% of Y?
X is what percent of Y?
Percentage increase or decrease
How to use the percentage calculator
- Pick the calculator that matches your question — percentage of a number, what percent, or percentage change.
- Enter your two values into the fields.
- The result updates live as you type — no button needed.
- For percentage change, a green result means an increase and a red result means a decrease.
Why use a percentage calculator?
Percentages show up everywhere — discounts at checkout, exam scores, tips, interest rates, sales growth, and body-weight targets. Doing the mental math quickly gets error-prone, especially with decimals. This tool covers the three calculations people need most, updates instantly as you type, and runs entirely in your browser so nothing you enter is ever sent anywhere. Results are provided for general and informational purposes only and are not a substitute for professional financial, accounting, or tax advice.
How do I calculate a percentage of a number?
Divide the percentage by 100, then multiply by the number. For example, 20% of 150 is (20/100) x 150 = 30. The first calculator on this page does this automatically as you type.
What is the formula for percentage increase or decrease?
Subtract the original value from the new value, divide by the original value, then multiply by 100: ((New - Old) / Old) x 100. A positive result is an increase, a negative result is a decrease.
Can I use decimals or negative numbers in this calculator?
Yes. All three calculators accept decimals and negative numbers, so you can work with real-world figures like prices, discounts, or year-over-year changes.