Percentage Calculator: Formulas and Practical Examples

What Is a Percentage?

A percentage is a way to express a number as a part of 100. The word percent means “per hundred.” For example, 25% means 25 out of every 100, or one quarter. Percentages are useful for marks, attendance, discounts, tax, salary changes, profit, and budgets.

How to Use the Multi-Tool Percentage Calculator

Choose a category or search for the calculation you need. Select a calculator card to open its form, enter the requested values, and press Calculate. The result panel shows the answer, formula, and a short explanation. Use Reset to clear that calculator's inputs. Closing a panel keeps its values until you reset them or clear all data.

How to Calculate a Percentage

To find a percentage of a number, divide the percentage by 100 and multiply by the number.

Percentage amount = (Percentage ÷ 100) × Number

For example, 20% of 500 is 0.20 × 500 = 100. To find what percentage one number is of another, divide the part by the total and multiply by 100. Therefore, 50 out of 200 is (50 ÷ 200) × 100 = 25%.

Percentage Increase vs. Percentage Decrease

Percentage increase and decrease compare a new value with an original baseline. Divide the difference by the original value and multiply by 100. An increase from 500 to 650 is (150 ÷ 500) × 100 = 30%. A decrease from 1,000 to 750 is (250 ÷ 1,000) × 100 = 25%. The original value must not be zero for the standard calculation.

Percentage Change vs. Percentage Difference

Percentage change uses the original value as the baseline, so it describes movement from one point to another. Percentage difference is a symmetric comparison between two values; it uses the absolute difference divided by the average of the two absolute values. Percentage points describe the direct subtraction of two percentages. A change from 10% to 12% is 2 percentage points, while the relative increase is 20%.

How to Calculate Exam Marks and Attendance

For exam marks, divide the marks obtained by the maximum marks and multiply by 100. A score of 420 out of 500 is 84%. For multiple subjects with different maximum marks, calculate the overall percentage using total marks obtained divided by total maximum marks. Do not simply average subject percentages unless each subject should have equal weight.

For attendance, divide classes attended by total classes held and multiply by 100. If you are below a target, the attendance calculator can estimate the number of additional classes you must attend in a row, assuming you do not miss any more classes.

How to Calculate Discounts and GST

For a discount, multiply the original price by the discount rate and subtract the savings from the original price. A 15% discount on ₹2,000 saves ₹300, leaving ₹1,700 to pay. Successive discounts apply one after another to the remaining price. A 20% discount followed by 10% off ₹1,000 leaves ₹720, which is an effective 28% discount—not 30%.

To add tax to a tax-exclusive amount, calculate the tax on the base amount and add it. To remove tax included in a price, divide the inclusive amount by 1 plus the tax rate expressed as a decimal. For example, ₹118 including 18% tax contains a ₹100 base and ₹18 tax. Actual tax treatment depends on the applicable rules and transaction.

How to Calculate Profit, Markup, and Margin

Profit is selling price minus cost price. Markup percentage divides profit by cost, while profit margin divides profit by selling price. If an item costs ₹800 and sells for ₹1,000, profit is ₹200, markup is 25%, and margin is 20%. These percentages use different baselines and should not be treated as interchangeable.

Common Percentage Formulas

• Percentage of a number: (Percentage ÷ 100) × Number
• Part as a percentage: (Part ÷ Total) × 100
• Percentage change: ((New − Original) ÷ Original) × 100
• Percentage difference: (Absolute difference ÷ Average of absolute values) × 100
• Discount amount: Original price × Discount rate ÷ 100
• Profit percentage: Profit ÷ Cost price × 100
• Weighted average: Sum of (Value × Weight) ÷ Sum of weights

Frequently Asked Questions

How do I calculate 20% of 500?

Divide 20 by 100 and multiply by 500. The answer is 100.

How do I find what percentage 50 is of 200?

Divide 50 by 200 and multiply by 100. The answer is 25%.

What is the difference between percentage points and percent?

Percentage points are the direct difference between two percentages. Moving from 10% to 12% is 2 percentage points, which is a 20% relative increase.

Can I calculate a percentage change from zero?

The standard percentage-change formula is undefined when the original value is zero because it would require division by zero. Compare the absolute difference instead.

Are two successive discounts added together?

No. Each discount applies to the price left after the previous discount. A 20% discount followed by 10% off is an effective 28% discount.

Does every institution use the same CGPA conversion?

No. Conversion rules vary by institution and grading system. Use the official rule supplied by your school, university, or examination board.

Does this calculator save my numbers?

Completed calculations are kept in the page's current session history only. The tool does not send calculation inputs to a server. Reset a calculator or use Clear all data to remove entered values.

Can I use this calculator on a mobile phone?

Yes. The calculator selector, inputs, and controls adapt to smaller screens and are designed for touch use.