Percentage Calculator
A percentage calculator is an essential tool for everyday math — whether you're calculating discounts while shopping, figuring out tax amounts, or analyzing data at work. Our free percentage calculator handles three common scenarios instantly: finding what percentage one number is of another, calculating a percentage of any number, and working out percentage increases or decreases.
How to Use
- Choose the tab that matches the question you want to answer. Use the first tab to find a percentage of a number, the second to find what percentage one value represents, and the third to calculate percentage change.
- Enter the required values in the input fields. Use plain numbers without percent signs or commas.
- Select Calculate to see the result, short explanation, and visual progress bar.
- For percentage change, positive results mean an increase and negative results mean a decrease.
Percentage Formulas
(Percentage / 100) × Total = Part
((New - Old) / Old) × 100 = % Change
The first formula compares a part with the whole and expresses that relationship out of 100. It is useful for scores, completion rates, and survey results. The second formula starts with a known percentage and total, then finds the matching part. This is common for discounts, tax, tips, and commissions. The third formula measures movement between an original value and a new value. If the answer is positive, the value increased. If it is negative, the value decreased. These formulas work because percentages are standardized ratios, making different quantities easier to compare.
Worked Example
You scored 45 out of 60 in a test. To find your percentage score, divide the marks scored by the total marks, then multiply by 100.
(45 / 60) × 100 = 75%
That means you earned 75 percent of the available marks. This method works for exams, assignments, sales targets, project completion, and any case where one number is part of a larger total.
Practical Percentage Tips
Percentages are easiest to verify with estimation before trusting a final number. Ten percent of a value is one tenth, so 10% of 800 is 80. Five percent is half of ten percent, so 5% of 800 is 40. Twenty percent is double ten percent, so 20% of 800 is 160. These mental checks help catch misplaced decimal points in tax, discounts, tips, and growth calculations. Percentage change also needs a clear original value. A rise from 50 to 100 is a 100% increase, but a fall from 100 to 50 is a 50% decrease. The direction matters because the base value changes. When comparing two percentage changes, always ask what each percentage is “of.” A 10% discount followed by 10% tax does not return to the original price because the second percentage applies to a smaller base. Write the base beside the calculation whenever the context is unclear. This habit makes percentage comparisons much easier to audit.
Fraction, Decimal and Percentage Reference
| Fraction | Decimal | Percentage |
|---|---|---|
| 1/2 | 0.5 | 50% |
| 1/4 | 0.25 | 25% |
| 1/3 | 0.333 | 33.33% |
| 3/4 | 0.75 | 75% |
| 1/5 | 0.2 | 20% |
| 1/10 | 0.1 | 10% |
| 2/3 | 0.667 | 66.67% |
| 1/8 | 0.125 | 12.5% |
FAQ
What is a percentage
A percentage is a way to express a number as a fraction of 100. The word means “per hundred,” so 25% means 25 out of every 100. Percentages make comparisons easier because they convert different totals to the same scale. For example, 45 out of 60 and 75 out of 100 are both 75%, even though the original totals are different.
How do I calculate percentage manually
To calculate a percentage manually, divide the part by the total and multiply the answer by 100. If you scored 36 marks out of 48, calculate 36 ÷ 48 = 0.75, then multiply by 100 to get 75%. For finding a percentage of a number, divide the percentage by 100 and multiply by the total.
What is the formula for percentage increase
The percentage increase formula is ((New value - Original value) ÷ Original value) × 100. It measures how much a value has grown compared with where it started. If a price rises from 500 to 600, the increase is 100. Divide 100 by 500 and multiply by 100 to get a 20% increase.
How do I find what percent one number is of another
Divide the first number by the second number, then multiply by 100. The first number is the part, and the second number is the total. For example, if 18 students in a class of 30 passed an exam, calculate 18 ÷ 30 × 100. The result is 60%, so 18 is 60 percent of 30.
What is the difference between percentage and percentile
A percentage shows a value out of 100. A percentile shows position compared with a group. If you score 80%, you answered 80 out of 100 marks correctly. If you are in the 80th percentile, you performed better than 80 percent of the comparison group. Percentile depends on other people’s scores, while percentage depends on your own total.