Percent · Increase · Decrease · Change
Example: What is 20% of 150?
This free Percentage Calculator handles every common percentage question in one place: finding what a percentage of a number is, working out what percent one number is of another, calculating percentage increase or decrease, and comparing the percentage change between two values. Whether you're working out a grade, a discount, a pay raise, or a statistic for a report, this tool gives you an instant, accurate answer without needing to remember the formula yourself. It's built for everyday use in the UK, USA and Canada, and works with any numbers, positive or negative, whole or decimal.
The core percentage formula is straightforward. To find what a percentage of a number is, divide the percentage by 100, then multiply it by the number. For example, to find 20% of 150, divide 20 by 100 to get 0.2, then multiply by 150 to get 30. This is the calculation used in shopping discounts, exam scores, tips, and countless everyday situations.
Sometimes you know two numbers and need to express one as a percentage of the other. To do this, divide the first number by the second number, then multiply the result by 100. For instance, if you scored 30 out of 150 on a test, divide 30 by 150 to get 0.2, then multiply by 100 to get 20%. This same method works for calculating market share, survey results, or any comparison between a part and a whole.
Percentage increase and decrease measure how much a value has changed relative to its starting point. Subtract the original value from the new value to find the difference, divide that difference by the original value, then multiply by 100. If the new value is higher than the original, the result is a positive percentage increase; if it's lower, the result is a negative percentage decrease. This calculation is widely used for salary raises, price changes, population growth, and investment returns.
| Scenario | Formula | Example |
|---|---|---|
| Percentage of a number | (percent ÷ 100) × number | 20% of 150 = 30 |
| What percent is X of Y | (X ÷ Y) × 100 | 30 of 150 = 20% |
| Percentage increase/decrease | ((new − old) ÷ old) × 100 | 150 → 180 = +20% |
These two terms are often confused but mean different things. Percentage change measures the relative difference between two values as a percentage of the original figure, using the formula above. Percentage points, on the other hand, simply measure the raw arithmetic gap between two percentages. For example, if an interest rate moves from 5% to 7%, that is a 2 percentage point increase, but it represents a 40% relative increase in the rate itself. Understanding this distinction matters most in finance, economics, and statistics, where the two figures can tell very different stories.
To find a percentage of a number, divide the percentage by 100 and multiply it by the number. For example, 20% of 150 is (20/100) x 150, which equals 30.
Divide the first number by the second number, then multiply the result by 100. For example, to find what percent 30 is of 150, calculate (30/150) x 100, which equals 20%.
Subtract the original value from the new value, divide that difference by the original value, then multiply by 100. A positive result is a percentage increase, and a negative result is a percentage decrease.
Percentage change measures the relative difference between two values as a percentage of the original value. Percentage points measure the simple arithmetic difference between two percentages, without dividing by the original value.