How to Calculate a Percentage: Formula, Examples & Easy Methods
Percentages are used in everyday life for shopping discounts, exam scores, financial calculations, statistics, business and many other situations. This guide explains how to calculate a percentage using simple formulas and examples.
Calculate a Percentage Quickly
Use our free Percentage Calculator to solve common percentage problems without doing the calculations manually.
Use the Percentage CalculatorWhat Is a Percentage?
A percentage is a way of expressing a number as a part of 100. The word "percent" means "per hundred." The percentage symbol is %.
For example, 25% means 25 parts out of 100. It can also be written as a fraction or decimal:
- 25% = 25/100
- 25% = 0.25
- 25% = one quarter
Basic Percentage Formula
The most common percentage formula is used when you know the part and the whole.
For example, if you scored 45 marks out of 60, you can calculate your percentage as follows:
Example: Exam Score
Part = 45
Whole = 60
Percentage = (45 ÷ 60) × 100
Percentage = 0.75 × 100
Percentage = 75%
How to Calculate a Percentage of a Number
To find a percentage of a number, convert the percentage into a decimal and multiply it by the number.
Example: 20% of 150
Convert 20% to a decimal:
20 ÷ 100 = 0.20
Multiply by 150:
0.20 × 150 = 30
20% of 150 = 30
How to Find What Percentage One Number Is of Another
Sometimes you want to know what percentage one number represents compared with another number.
Example: 30 is What Percentage of 120?
Percentage = (30 ÷ 120) × 100
Percentage = 0.25 × 100
Percentage = 25%
How to Calculate Percentage Increase
Percentage increase tells you how much a value has increased compared with its original value.
Example: Price Increase
Suppose a product originally costs $80 and its price increases to $100.
Original value = $80
New value = $100
Difference = $100 − $80 = $20
Percentage Increase = ($20 ÷ $80) × 100
Percentage Increase = 25%
How to Calculate Percentage Decrease
Percentage decrease shows how much a value has decreased compared with its original value.
Example: Price Discount
Suppose a product originally costs $100 and the sale price is $75.
Original value = $100
New value = $75
Difference = $100 − $75 = $25
Percentage Decrease = ($25 ÷ $100) × 100
Percentage Decrease = 25%
How to Calculate a Discount Percentage
Percentage calculations are commonly used when shopping. You can calculate the discount percentage by comparing the original price with the sale price.
Example: 20% Discount
Suppose a product costs $200 and has a 20% discount.
Discount = 20% of $200
Discount = 0.20 × $200
Discount = $40
Sale Price = $200 − $40
Sale Price = $160
Percentage Examples in Everyday Life
Percentages are used in many everyday situations, including:
- Calculating exam and test scores
- Finding shopping discounts
- Calculating taxes and tips
- Comparing price changes
- Understanding financial interest rates
- Analyzing business and sales data
- Calculating statistics and survey results
- Comparing increases and decreases
Percentage Formula Quick Reference
| Calculation | Formula |
|---|---|
| Basic Percentage | (Part ÷ Whole) × 100 |
| Percentage of a Number | (Percentage ÷ 100) × Number |
| Percentage Increase | ((New − Original) ÷ Original) × 100 |
| Percentage Decrease | ((Original − New) ÷ Original) × 100 |
| Discount Percentage | ((Original − Sale) ÷ Original) × 100 |
Percentage vs Percentage Points
Percentage and percentage points are not always the same thing. Percentage points describe the direct difference between two percentages.
For example, if an interest rate changes from 5% to 7%, the increase is 2 percentage points.
However, the percentage increase relative to the original 5% is:
Therefore, the rate increased by 2 percentage points, which represents a 40% increase relative to the original rate.
Common Percentage Calculation Mistakes
Percentage problems are usually straightforward, but a few common mistakes can lead to incorrect results.
- Using the wrong number as the original or whole value.
- Forgetting to divide by 100 when converting a percentage to a decimal.
- Confusing percentage points with percentage change.
- Using the final value instead of the original value when calculating percentage increase or decrease.
- Rounding numbers too early during a calculation.
How to Use Our Percentage Calculator
If you don't want to calculate percentages manually, you can use our free Percentage Calculator.
- Open the Percentage Calculator.
- Enter the numbers required for your calculation.
- Select or use the appropriate percentage calculation.
- Click the calculate button.
- Review your result.
Try the Free Percentage Calculator
Calculate percentages quickly and easily with our free online tool.
Calculate PercentagePercentage Increase & Decrease Calculator
If you need to compare an original value with a new value, our Percentage Increase & Decrease Calculator can calculate the percentage change quickly.
It can be useful for comparing price changes, sales figures, scores, measurements and other numerical values.
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Percentage Calculator FAQs
What is the basic percentage formula?
The basic percentage formula is: Percentage = (Part ÷ Whole) × 100.
How do I calculate a percentage of a number?
Convert the percentage to a decimal and multiply it by the number. For example, 20% of 150 is 0.20 × 150 = 30.
How do I calculate percentage increase?
Use the formula: ((New Value − Original Value) ÷ Original Value) × 100.
How do I calculate percentage decrease?
Use the formula: ((Original Value − New Value) ÷ Original Value) × 100.
What is 20% of 100?
20% of 100 is 20.
What is 25% of 200?
25% of 200 is 50.
What is the difference between percentage and percentage points?
Percentage points show the direct difference between two percentages, while percentage change measures the relative change from the original value.
Final Thoughts
Learning how to calculate percentages is useful for school, work, shopping, finance and everyday decision-making. The basic formula is simple, and many percentage calculations can be solved with a few steps.
When you need a quick result, use the free Percentage Calculator on Easy Online Tool.
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