How To Calculate a Percentage (With Examples)
What Is a Percentage?
A percentage expresses a number or ratio as a fraction of 100. The symbol % means “per hundred.”
For example:
- 50% means 50 out of 100.
- 25% means 25 out of 100, or one-quarter.
- 150% means 150 out of 100, or 1.5 times the original value.
Percentages are commonly used in budgets, discounts, taxes, performance reports, survey results and financial comparisons.
Basic Percentage Formula
To determine what percentage one number represents of another, use:
Percentage = (Part ÷ Whole) × 100
The part is the amount you are measuring. The whole is the total amount.
For example, if 36 of 48 employees completed a survey:
Percentage = (36 ÷ 48) × 100
Percentage = 0.75 × 100
Percentage = 75%
Therefore, 75% of employees completed the survey.
How To Convert a Decimal to a Percentage
Multiply the decimal by 100 and add the percentage symbol.
Example:
0.62 × 100 = 62%
Moving the decimal point two places to the right produces the same result.
Additional examples:
- 0.08 = 8%
- 0.375 = 37.5%
- 1.25 = 125%
How To Convert a Fraction to a Percentage
First divide the numerator by the denominator. Then multiply the decimal result by 100.
For example, convert 3/20 to a percentage:
3 ÷ 20 = 0.15
0.15 × 100 = 15%
Therefore, 3/20 equals 15%.
How To Convert a Percentage to a Decimal
Divide the percentage by 100 or move the decimal point two places to the left.
Examples:
- 45% = 0.45
- 8% = 0.08
- 125% = 1.25
This conversion is useful when multiplying a number by a percentage.
Three Common Types of Percentage Problems
Finding the percentage
Question: What percentage of 80 is 56?
Formula:
Percentage = (Part ÷ Whole) × 100
Calculation:
(56 ÷ 80) × 100 = 70%
Answer: 56 is 70% of 80.
Finding the part
Question: What is 30% of 250?
Formula:
Part = Percentage as a decimal × Whole
Calculation:
0.30 × 250 = 75
Answer: 30% of 250 is 75.
Finding the whole
Question: 45 is 15% of what number?
Formula:
Whole = Part ÷ Percentage as a decimal
Calculation:
45 ÷ 0.15 = 300
Answer: 45 is 15% of 300.
How To Calculate a Discount
First calculate the discount amount, then subtract it from the original price.
Suppose a $160 product is discounted by 25%.
Discount amount:
$160 × 0.25 = $40
Sale price:
$160 − $40 = $120
The sale price is $120.
You can also multiply the original price by the percentage remaining:
100% − 25% = 75%
$160 × 0.75 = $120
How To Find the Original Price After a Discount
Suppose a product costs $120 after a 30% discount.
A 30% discount means the sale price is 70% of the original price.
Original price:
$120 ÷ 0.70 = $171.43
The original price was approximately $171.43.
A common mistake is dividing the sale price by the discount percentage. You must divide by the percentage of the original price that remains.
How To Calculate a Percentage Increase
Use:
Percentage increase = ((New value − Original value) ÷ Original value) × 100
Suppose monthly website traffic increases from 8,000 to 10,000 visits.
Difference:
10,000 − 8,000 = 2,000
Divide by the original value:
2,000 ÷ 8,000 = 0.25
Convert to a percentage:
0.25 × 100 = 25%
Website traffic increased by 25%.
How To Calculate a Percentage Decrease
Use:
Percentage decrease = ((Original value − New value) ÷ Original value) × 100
Suppose customer complaints decrease from 240 to 180.
Difference:
240 − 180 = 60
Divide by the original value:
60 ÷ 240 = 0.25
Convert to a percentage:
0.25 × 100 = 25%
Customer complaints decreased by 25%.
Percentage Change vs. Percentage-Point Change
These calculations are not the same.
Suppose a conversion rate increases from 20% to 25%.
The percentage-point increase is:
25% − 20% = 5 percentage points
The percentage increase is:
((25 − 20) ÷ 20) × 100 = 25%
Therefore, the rate increased by five percentage points, which represents a 25% increase relative to the original rate.
How To Calculate Percentage Difference
Percentage difference compares two values when neither value is treated as the original baseline.
Use:
Percentage difference = (Absolute difference ÷ Average of the two values) × 100
Suppose one supplier charges $25 and another charges $30.
Absolute difference:
|30 − 25| = 5
Average:
(30 + 25) ÷ 2 = 27.5
Percentage difference:
(5 ÷ 27.5) × 100 = 18.18%
The percentage difference is approximately 18.18%.
This differs from percentage increase. If the price rose from $25 to $30, the percentage increase would be:
((30 − 25) ÷ 25) × 100 = 20%
Percentage Calculation Examples
Example 1: Calculating a test score
An employee answers 42 of 50 training questions correctly.
(42 ÷ 50) × 100 = 84%
The employee’s score is 84%.
Example 2: Calculating a commission
A salesperson receives a 6% commission on $18,000 in sales.
$18,000 × 0.06 = $1,080
The commission is $1,080.
Example 3: Adding sales tax
A product costs $85, and the sales tax rate is 7%.
Tax:
$85 × 0.07 = $5.95
Total:
$85 + $5.95 = $90.95
The total price is $90.95.
Example 4: Calculating a salary increase
An employee’s salary increases from $60,000 to $64,500.
Difference:
$64,500 − $60,000 = $4,500
Percentage increase:
($4,500 ÷ $60,000) × 100 = 7.5%
The salary increased by 7.5%.
Example 5: Calculating a profit margin
A product sells for $100 and produces $35 in profit.
Profit margin:
($35 ÷ $100) × 100 = 35%
The profit margin is 35%.
Example 6: Calculating a completion rate
A team completes 68 of 80 planned tasks.
(68 ÷ 80) × 100 = 85%
The completion rate is 85%.
Example 7: Calculating market share
A company sells 12,000 units in a market with total sales of 80,000 units.
(12,000 ÷ 80,000) × 100 = 15%
The company has a 15% market share.
How To Calculate Percentages in Excel or Google Sheets
If the part is in cell A2 and the whole is in B2, enter:
=A2/B2
Then format the result as a percentage.
To calculate 20% of the value in A2:
=A2*20%
To calculate percentage change from the old value in A2 to the new value in B2:
=(B2-A2)/A2
Format the result as a percentage.
Common Percentage Mistakes
Using the wrong whole
The denominator should represent the complete group or original baseline relevant to the question.
Forgetting to convert the percentage
When multiplying, convert 15% to 0.15 unless your calculator or spreadsheet accepts the percentage symbol directly.
Dividing by the new value
Percentage change normally uses the original value as the denominator.
Confusing percentage change with percentage points
An increase from 10% to 15% is five percentage points but a 50% relative increase.
Reversing discounts
A 20% decrease followed by a 20% increase does not return to the original value. If $100 falls by 20%, it becomes $80. Increasing $80 by 20% produces $96.
Rounding too early
Keep additional decimal places during the calculation and round the final result. Early rounding can create avoidable errors in financial or analytical work.
Turn Percentage Data Into Presentations With Dokie
Percentage calculations often appear in sales reports, campaign analyses, financial updates and performance reviews. Dokie is an AI presentation maker that transforms documents, URLs, research and notes into structured, business-ready slides, helping teams explain numerical findings clearly.
You can apply a custom template, revise the generated content and export the presentation as an editable PowerPoint file. Dokie is useful for turning spreadsheet findings and business metrics into reports that remain accurate, polished and easy to present.
Frequently Asked Questions
Why do you multiply by 100 when calculating a percentage?
A decimal expresses a value relative to one, while a percentage expresses it relative to 100. Multiplying by 100 converts between these formats.
Can a percentage be greater than 100%?
Yes. A percentage above 100% means the value is greater than the reference amount. For example, 150% of 80 is 120.
What is the easiest way to find 10% of a number?
Divide the number by 10. For example, 10% of 450 is 45.
How do you calculate a percentage without a calculator?
Use simple benchmark percentages. Find 10% by dividing by 10, 1% by dividing by 100 and 50% by dividing by two, then combine those values as needed.