How To Calculate Percentages?

Percentages are crucial in many business fields for analyzing performance, growth, and profitability because they provide a standardized way to express proportions, such as discounts, growth rates, profit margins, and market share. Common problems like profit margins, discount percentages, and growth rates are often handled using basic percentage formulas. Understanding and applying these calculations helps make informed decisions in business operations.
In the following lines, we will expand on all the details related to calculating percentages.

 

What is a percentage?

A percentage expresses a value as a fraction of 100. It is a ratio of a part to a whole, representing the whole by 100. Percentages are often used to describe changes, proportions, or rates. The term percentage comes from “per centum.”

Here are some examples of percentages:

  • 5% = 5/100 ( = 1/20 (or) 0.05)
  • 25% = 25/100 ( = 1/4 (or) 0.25)
  • 30% = 30/100 ( = 0.30)
  • 50% = 50/100 ( = 1/2 (or) 0.5)

 

How to calculate a percentage?

To calculate a percentage, follow these simple steps:

  1. Determine the part and the whole:
    Identify the value you want to find: the percentage of (the part) and the total value (the whole).
    If we want to calculate 25 percent, the part is 25, and the whole is 100.

  2. Divide the part by the whole:
    Divide the part by the whole to get a decimal value.
    Divide the part by the whole: 25 ÷ 100 = 0.25

  3. Multiply by 100:
    Multiply the decimal value by 100 to convert it to a percentage.
    Multiply by 100: 0.25 × 100 = 25%

 

What is the percentage formula?

The percentage formula is:

Percentage = (Part ÷ Whole) × 100

Where:

  • Part is the value you want to find the percentage of
  • Whole is the total value
  • Percentage is the result, expressed as a percentage

 

What types of percentage problems exist?

Let’s dive into the several types of percentage problems that are known.

  1. Finding a percentage of a number
    Formula: Percentage (%)= Part/Total×100 or Part = Percentage(%)/Total
    Example: What is 25% of 200?
    Solution: 25% of 200 = 0.25 × 200 = 50

  2. Finding the part when the percentage and whole are known
    Formula: Part = Percentage/100 × Whole
    Example: What is 30% of 150?
    Solution 30/100 × 150 = 45

  3. Finding the whole when the part and percentage are known
    Whole = Part/ (Percentage/100)
    Example: 25 is 20% of what number?
    Solution: Whole = 25/(20/100)=125

  4. Finding the percentage increase
    Formula: Percentage decrease (%)= (Initial value - Final value)/Initial value × 100
    Example: A company's profits increased from 100,000 to 120,000. What is the percentage increase?
    Solution: Increase = 120,000 - 100,000 = 20,000
    Percentage increase = (20,000 ÷ $100,000) × 100 = 20%
  1. Finding the percentage decrease
    Formula: Percentage increase (%)= (Final value - Initial value) /Initial value × 100
    Example: A shirt costs 80 and is on sale for 60. What is the percentage decrease?
    Solution: Percentage decrease = ((80 – 60) ÷ $80) × 100 = 25%

  2. Finding the percentage of a total
    Formula: Percentage (%)= Part/Total×100
    Example: A survey of 100 people found that 25 people liked a new product. What percentage of people liked the product?
    Solution: Percentage = (25 ÷ 100) × 100 = 25%

  3. Finding the original value from a percentage
    Formula: New Value=(1-Percentage) × Original Value
    Example: A shirt is on sale for 25% off its original price. The discounted price is $80. What was the original price?
    Solution: Using the formula mentioned above, we have:
    80 = (1-0.25) × Original price
    Original price = 80 ÷ 0.75 = $106.67

  4. Finding the percentage change
    Percentage change is the difference between two values, expressed as a percentage of the original value.
    Formula: Percentage Change = ((New Value - Old Value) ÷ Old Value) × 100
    Example: A car costs $8000 and is on sale for $6000. What is the percentage change?
    Percentage Change = ((6000 - 8000) ÷ $8000) × 100 = -25%

 

Common problems with percentages in real life and business

The best way to understand how to apply percentage calculation in day-to-day use is to have specific examples that you can apply at work of home. We have compiled a selection with 10 problems, their solutions and the metod to reach the answer.

1. Product Sales

Problem: A smartphone is on sale for 20% off its original price of $800. How much will you pay for the smartphone?

Solution:

  • Calculate the discount: 20% of 800 = 0.20 × 800 = $160
  • Subtract the discount from the original price: 800 - 160 = $640

Answer: You will pay $640 for the smartphone.


2. Tips and Gratuities

Problem: If your restaurant bill is $50 and you want to leave a 15% tip, how much will you pay in total?

Solution:

  • Calculate the tip: 15% of 50 = 0.15 × 50 = $7.50
  • Add the tip to the bill: 50 + 7.50 = $57.50

Answer: You will pay $57.50 in total.


3. Interest Rates

Problem: You deposit $1,000 into a savings account with a 5% annual interest rate. How much will you have in the account after one year?

Solution:

  • Calculate the interest: 5% of 1,000 = 0.05 × 1,000 = $50
  • Add the interest to the principal: 1,000 + 50 = $1,050

Answer: You will have $1,050 in the account after one year.


4. Percentage Increase

Problem: A company's profits increased from 100,000 to 120,000. What is the percentage increase?

Solution:

  • Calculate the difference: 120,000 - 100,000 = $20,000
  • Calculate the percentage increase: (20,000 ÷ 100,000) × 100 = 20%

Answer: The company's profits increased by 20%.


5. Percentage Decrease

Problem: The number of employees decreased from 80 to 60. What is the percentage decrease?

Solution:

  • Calculate the difference: 80 - 60 = 20
  • Calculate the percentage decrease: (20 ÷ 80) × 100 = 25%

Answer: The company has 25% fewer employees than it had initially.


6. Calculating Profit Margin

Problem: A business has $5000 in revenue and $1500 in profit. What is the profit margin?

Formula: Profit margin = Profit / Revenue ×100

Solution: Profit Margin=(1500/5000)×100=30%

Answer: The profit margin for a business with $5000 revenue and $1500 profit is 30%.


7. Calculating Discount Percentage

Problem: A product originally priced at $200 is on sale for $160. What is the discount percentage?

Formula: Discount Percentage=((Original Price−Sale Price)/Original Price)×100

Solution: Discount Percentage=(200−160)/200)×100=20%

Answer: The discount percentage for a product that went from $200 to $160 is 20%


8. Calculating Growth Rate

Problem: A company’s revenue grew from $50,000 to $60,000. What is the growth rate?

Formula: Growth Rate=((New Value−Old Value)/Old Value)×100

Solution: Growth Rate=((60,000−50,000)/50,000)×100=20%

Answer: The growth rate for a company that went from $50k to $60k is 20%.


9. Calculating Percentage Change in Costs

Problem: If the cost of raw materials increases from $4000 to $5000, what is the percentage change between the old and new costs?

Formula: Percentage Change=((New Cost−Old Cost)/Old Cost)×100

Solution: Percentage Change=(5000−4000)/4000)×100=25%

Answer: The increase in raw materials represents a 25% percentage change in costs.


10. Calculating Market Share

Example: A company generates $500,000 in sales while the total market sales are $2,000,000. What is the company’s market share?

Formula: Market Share=(Company’s Sales/Total Market Sales)×100

Solution: Market Share=(500,000/2,000,000)×100=25%

Answer: The market share of a company generating $0.5M out of a $2M market is 25%.

 

Percentage chart with fractions and percentages:

A percentage chart can help you make the percentage calculations much faster.

Fraction

Percentage

1/2

50%

1/3

33.33%

2/3

66.67%

1/4

25%

3/4

75%

1/5

20%

2/5

40%

3/5

60%

4/5

80%

1/6

16.67%

2/6

33.33%

3/6

50%

4/6

66.67%

5/6

83.33%

 


FAQ Percentages

How to convert between percentages and decimals:

To convert a percentage to a decimal, divide the percentage by 100.

  • Example: 25% = 25 ÷ 100 = 0.25
  • Example: 50% = 50 ÷ 100 = 0.5

 

How to convert between percentages and decimals?

To convert a decimal to a percentage, multiply the decimal by 100.

  • Example: 0.25 = 0.25 × 100 = 25%
    Example: 0.5 = 0.5 × 100 = 50%

 

How to convert fractions to percentages?

To convert a fraction to a percentage, divide the numerator (top number) by the denominator (bottom number) and multiply by 100.

Example: 3/4 = (3 ÷ 4) × 100 = 75%

 

What are the differences between percentage and percent?
Percentage and percent are often used interchangeably, but there is a subtle difference:

Percentage is a specific value or amount expressed as a fraction of 100.

Example:
"The percentage of students who passed the exam is 80%" (referring to a specific value).

Percent is a unit of measurement used to express a proportion or rate.

Example:
"The interest rate is 5 percent per annum" (referring to a unit of measurement).

 

What percent of X is Y?

To calculate what percent of X is Y, we use this formula (Y/X)*100 = P%.

For example John worked this week 25 hours out of 40 that is standard. What percent is 25 out of 40 hours weekly? (25/40)*100 = 62.5%.

 

What is 16 out of 20 as a percentage?

Let's use again the formula (Y/X)*100 = P%.

16/20 * 100 = 0.8 * 100 = 80%.

 

What is X is percent of Y?

To find out X if it is P% of Y, we use this formula: Y/P% = X.

For example, $5000 is 20% of what amount?

X = $5000/20% = $5000/(20/100) = $5.000/0.20 = $250.000.

So, $5000 is 20% of $250.000.

 

How do you calculate 20% in Excel?

To figure out 20% in Excel, apply the formula "=number*0.2". Replace "number" with the exact value you want to compute 20% of. Multiplying the integer by 0.2 yields a result that is 20% of the original value.

If you want to calculate 20% of $75, then you will get the result by writing = $75 *0.2 = 15

Tip: We expand on this topic on this dedicated article: How to calculate percentages in Excel?

 

X is what percent of Y?

For example, 21 days is what percent of 31 days?

We have the following formula: Y = P% * X, this means that P% = Y÷X.

In this sense, 21/31 = 0.67%.

Convert the decimal to percent P% = 0.67 * 100 = 67%

Therefore, 21 is 67% of 31.

 

X is P percent of what?

We start with the equation: X = P% * Y.

For example, the department A has 15 employees which is 60% of the total workforce, and we need to know the number of total employees.

In this case X = 15 ÷ 60%. In this sense 15/0.6 = 25. So, 15 employees is 60% of 25 employees total.

 

Key takeaways on percentages:

  1. A percentage is a way to express a value as a fraction of 100.
  2. To convert a percentage to a decimal, divide by 100. To convert a decimal to a percentage, multiply by 100.
  3. To calculate the percentage increase, divide the difference by the original value and multiply by 100.
  4. To calculate the percentage decrease, divide the difference by the original value and multiply by 100.
  5. Percentages are used in discounts, sales, tips, interest rates, etc.
  6. Percentage refers to a specific value or amount, while percent is a unit of measurement.
  7. A percentage calculator helps, especially when working with large numbers or complex calculations.

By understanding these key points and practicing real-life problems, you can gain confidence and proficiency in working with percentages. Regular practice with real-life problems will help you apply percentage calculations to various situations with ease.