What Is a Percentage?

A percentage expresses a value as a part of 100. The word “percent” means “per hundred,” so 25% represents 25 parts out of 100. Percentages are used in shopping discounts, school results, business reports, budgets, statistics and many everyday comparisons. This free percentage calculator helps you work through four common tasks: finding a percentage of a number, calculating what percentage one number is of another, measuring percentage increase or decrease, and finding the percentage difference between two values. Enter the numbers in the calculator and select the calculation that matches your question.

How to Use the Percentage Calculator

1. Select the type of calculation from the dropdown list.
2. Enter the two numbers in the labelled fields.
3. Click Calculate to display the result and the formula used.
4. Check that the selected calculation matches the question you are trying to answer.
5. Choose Clear to start a new calculation.

The tool runs calculations in your browser. It does not need an account or a separate spreadsheet, and it can be used on desktop or mobile screens. For important financial decisions, verify the result and make sure you are using the correct starting value, tax basis or rounding rule.

Four Types of Percentage Calculations

1. What is X% of Y?

Use this when you need to find a portion of a number. For example, 15% of 200 is 30. The formula is percentage divided by 100, multiplied by the number: (15 ÷ 100) × 200 = 30. This calculation is useful for estimating discounts, commissions, tips or portions of a budget.

2. X is what percent of Y?

Choose this option when you know a part and a whole and want to express the part as a percentage. For example, 30 is 15% of 200 because (30 ÷ 200) × 100 = 15%. Students can use this method to understand marks, while teams may use it to compare completed work with a total target.

3. Percentage increase or decrease

Percentage change compares a starting value with a new value. Subtract the starting value from the new value, divide the difference by the absolute starting value, then multiply by 100. If a price moves from 80 to 100, the increase is 25%. If it moves from 100 to 80, the decrease is 20%. The starting point matters, so reversing the values can produce a different percentage.

4. Percentage difference

Percentage difference compares two values without treating one as the original starting value. This calculator divides the absolute difference by the average of the absolute values and multiplies by 100. It can be useful when comparing two measurements or values that have equal status. It is different from percentage change, which uses a defined starting value.

Everyday Uses for Percentages

Shoppers can estimate a sale discount and compare prices. Students can calculate marks as a share of total marks. Households can work out how much of a monthly budget goes toward a category. Businesses may compare sales figures, costs or progress against a target. These examples rely on the same basic idea: expressing a relationship in parts per hundred. Be careful when comparing percentages from different bases. A 10% discount on a low-priced item is not the same amount of money as a 10% discount on an expensive item. Similarly, an increase of 10% followed by a decrease of 10% does not return a value to its original amount.

Percentage Change vs. Percentage Difference

These terms are related but not interchangeable. Percentage change is used when there is a clear before-and-after relationship, such as a price changing from last month to this month. Percentage difference is useful when comparing two values without choosing either one as the baseline. If a report asks for a percentage change, use the original value as the starting point rather than the average.

Frequently Asked Questions

Is this percentage calculator free?

Yes. The calculator is available without a subscription or account.

Can I calculate a discount?

Yes. Select “What is X% of Y?” and enter the discount rate as X and the original price as Y. The result is the discount amount; subtract it from the original price to find the price after discount.

Why can’t I calculate percentage change from zero?

Percentage change divides by the starting value. When that value is zero, the formula would require division by zero, so the percentage change is undefined.

Why is percentage difference different from percentage change?

Percentage change uses a defined starting value as its base. Percentage difference uses the average of the compared values, so it is designed for comparisons where neither value is the starting point.

Can I use decimal values?

Yes. You can enter decimals and negative values where appropriate. Make sure the values make sense for your particular problem and review any rounding required by your assignment or workplace.

Check the Context Before Using a Result

Percentages are simple once the right formula is chosen, but a correct calculation can still answer the wrong question if the wrong base is selected. Decide whether you need a portion, a ratio, a change from an original value or a comparison between two equal values. Then enter your numbers above and review the displayed formula along with the result.

Related Tools

Explore these related free tools: Percentage Change Calculator · Average Calculator · Discount Calculator.