Percentage Calculator
Find what X% of Y is, what percentage X is of Y, or the percentage change between two numbers.
Assumptions used in this calculation
- Percentage change direction: Percentage increase/decrease/difference always uses the first value entered as the original (base) value, so swapping the two inputs changes the result, this matches the standard convention but can surprise users comparing in the opposite direction.
About this calculator
Percentage problems show up constantly in everyday life, working out a discount at checkout, checking how much a bill increased, figuring out a test score, or comparing two numbers as a ratio, and while the arithmetic is simple, it's easy to apply the wrong formula or divide by the wrong number under time pressure. This calculator covers the core percentage questions in one place: finding what X% of Y is, finding what percentage one number is of another, and calculating the percentage increase, decrease or difference between two values, switching between them automatically based on what you're trying to find. It's built for anyone who needs a fast, reliable answer without re-deriving the formula each time, students checking homework, shoppers comparing sale prices, or professionals sanity-checking a spreadsheet figure. The most common mistake with percentage change specifically is dividing by the wrong value (new instead of original), which this calculator handles correctly and consistently every time.
Worked example
What is 20% of 150?
Result: 30
How to use this
- 1Choose the type of percentage calculation you need (X% of Y, what % is X of Y, or percentage change).
- 2Enter the numbers.
- 3Read the result instantly as you type.
Troubleshooting
Not sure which calculation mode I need.
Each mode is labeled with an example, if you're increasing/decreasing a value by a %, use the "percentage change" mode specifically.
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