How to Calculate Percentage: Simple Steps, Formulas, and Real Examples

Percentages show up everywhere. You see them in discounts, exam scores, salary increases, taxes, interest rates, and business reports. When you understand how to calculate percentage, you can make faster decisions and double check numbers without confusion.

This guide explains three percentage calculations that cover almost every everyday use case. You will learn how to calculate a percentage of a number, how to find what percent one number is of another, and how to calculate percentage change. You will also see practical examples and a quick way to verify results using a free online percentage calculator.

What Is a Percentage

A percentage is a way to express a part of a whole using a base of one hundred. The word percent means per hundred, so twenty five percent means twenty five out of one hundred.

Percentages help you compare values even when totals are different. For example, scoring forty five out of fifty and ninety out of one hundred are both ninety percent. That tells you the performance level is the same even though the totals are different.

Character Count vs Word Count

Percentages are often used when writing or editing content too, especially for growth comparisons, conversion rates, and performance reporting. If you publish content regularly, you may also measure length in words and characters for titles, descriptions, and short form text.

If you want a clear explanation of the difference, you can read: Blog.

The Three Most Useful Percentage Calculations

Most real world percentage problems fit into one of these categories:

• Finding a percentage of a number, such as “What is fifteen percent of eighty?”
• Finding what percent one number is of another, such as “Twenty is what percent of eighty?”
• Finding percentage change, such as “What is the percentage increase from eighty to one hundred?”

Your site already supports these three forms in one place, which makes it easier for users to get the exact result they need. You can use the calculator directly here: Percentage Calculator.

1) How to Calculate a Percentage of a Number

This is the most common percentage calculation. You use it when you need to find a portion of a value. Examples include discounts, tips, taxes, and commission amounts.

The Formula

Percentage of a number = (Percentage ÷ 100) × Whole

Step by Step Example

Problem: What is twenty percent of two hundred?

Step 1: Convert the percentage to a decimal. Twenty percent becomes 20 ÷ 100 = 0.2

Step 2: Multiply by the whole. 0.2 × 200 = 40

Answer: Twenty percent of two hundred is forty.

Real Use Cases

• Discounts: Ten percent off a 5,000 price means 500 discount.
• Tips: Fifteen percent tip on a 3,200 bill means 480 tip.
• Taxes: Eight percent tax on a 12,000 purchase means 960 tax.
• Business: Two percent fee on a 150,000 invoice means 3,000 fee.

2) How to Find What Percent One Number Is of Another

This calculation answers questions like “X is what percent of Y?” It is useful for grades, completion rates, survey results, and comparing parts to a total.

The Formula

Percentage = (Part ÷ Whole) × 100

Step by Step Example

Problem: Twenty five is what percent of two hundred?

Step 1: Divide part by whole. 25 ÷ 200 = 0.125

Step 2: Multiply by one hundred. 0.125 × 100 = 12.5

Answer: Twenty five is 12.5 percent of two hundred.

Real Use Cases

• Exam score: 42 correct answers out of 60 equals 70 percent.
• Task completion: 18 completed tasks out of 24 equals 75 percent.
• Inventory: 30 sold out of 120 total equals 25 percent sold.
• Marketing: 250 sign ups out of 5,000 visits equals 5 percent conversion.

3) How to Calculate Percentage Change

Percentage change shows how much a value increases or decreases relative to the original value. This is the calculation used for growth rates, inflation, price changes, and performance comparisons.

The Formula

Percentage change = ((New value − Old value) ÷ Old value) × 100

Step by Step Example

Problem: A price increases from 80 to 100. What is the percentage increase?

Step 1: Find the difference. 100 − 80 = 20

Step 2: Divide by the old value. 20 ÷ 80 = 0.25

Step 3: Multiply by one hundred. 0.25 × 100 = 25

Answer: The value increased by 25 percent.

Increase vs Decrease

If the new value is higher than the old value, the result is a percentage increase. If the new value is lower, the result is a percentage decrease.

For a clear explanation with an example, you can also read: Understanding Percentage Increase and Decrease.

Quick Reference Table

Question Type	What You Want to Find	Formula	Common Examples
What is X% of Y?	Portion of a number	(X ÷ 100) × Y	Discounts, tips, taxes
X is what % of Y?	Percent that a part represents	(X ÷ Y) × 100	Grades, completion rates
Percentage change	Increase or decrease relative to old value	((New − Old) ÷ Old) × 100	Growth, pricing, analytics

Common Mistakes and How to Avoid Them

Percentage mistakes usually happen for simple reasons. If you keep these points in mind, you will avoid most errors.

• Mixing up the whole and the part: Always confirm which number is the total and which is the portion.
• Using the wrong base for percentage change: Percentage change uses the old value in the denominator, not the new value.
• Forgetting to multiply by one hundred: If you stop at the decimal, you have a proportion, not a percentage.
• Confusing percentage with percentage points: Going from 40 percent to 50 percent is a change of 10 percentage points, but it is a 25 percent increase relative to 40 percent.

Practical Examples You Can Reuse

If you want quick practice problems that mirror real situations, use these examples and verify them using the tool on the homepage.

• What is 12 percent of 4,500?
• 320 is what percent of 1,600?
• Sales grew from 75,000 to 96,000. What is the percentage increase?
• A bill drops from 2,400 to 1,920. What is the percentage decrease?

To verify any result, use: Percentage Calculator.

Frequently Asked Questions

How do I calculate a percentage quickly without doing the math manually

You can use a free online calculator that supports all three common percentage problems. On this site, you can calculate “What is X% of Y,” “X is what percent of Y,” and percentage change instantly: Free Percentage Calculator.

Can a percentage be more than one hundred

Yes. If a part is larger than the whole, the result can exceed one hundred percent. For example, if you earned 120 points out of a 100 point target, that is 120 percent of the target.

What is the easiest way to calculate percentage increase or decrease

Use the percentage change formula with the old value as the base, or use the dedicated percentage change section on the homepage: Percentage Change Calculator.

How do I calculate a discount percentage

If you want the discount amount, calculate “discount percent of original price.” If you want the final price, subtract the discount amount from the original price. You can do both quickly using the “What is X% of Y?” tool: Discount Percentage Calculation.

Conclusion

Once you understand the three core calculations, percentage math becomes simple. Use “What is X% of Y?” to find a portion, use “X is what percent of Y?” to find the percentage that a part represents, and use percentage change to measure growth or decline over time.

If you want fast results without manual steps, you can calculate everything instantly using the tools on the homepage: Free Percentage Calculator.

Related Articles

• Understanding Percentage Increase and Decrease
• Quick Percentage Tips for Restaurant Tipping
• Browse all percentage tutorials on the blog