Percentage Calculator: How to Calculate a Percentage?

Percentages are everywhere – from shopping discounts and tracking weight loss to calculating savings interest and business profits. Knowing how to calculate percentages helps you make smarter financial and health decisions.

If you want quick answers, try our instant percentage calculator, or read on for a simple, step-by-step guide!

What is a Percentage?

A percentage is a way to express a number as a fraction of 100. It is represented by the % symbol and is commonly used to compare values and measure changes.

For example

If you scored 85% on your Leaving Cert Maths exam, that means you got 85 out of 100 questions correct.

How to Calculate a Percentage?

You can find a percentage using this simple formula:

Percentage = (Part ÷ Total) × 100

For example

Say you have 10 biscuits, and you eat 4 of them. To find the percentage you ate:

• Divide the part by the total: 4 ÷ 10 = 0.40
• Multiply by 100: 0.40 × 100 = 40%

So, you ate 40% of the biscuits.

How to Calculate a Percentage Increase?

A percentage increase tells you how much something has grown compared to its original value. This is useful when calculating salary increases, rent hikes, or price rises.

Formula for Percentage Increase

Percentage Increase = ((New Value - Old Value) ÷ Old Value) × 100

How to Calculate a Percentage Increase?

Your monthly electricity bill was €120 last year, but this year it's gone up to €150.

• Find the increase in cost: €150 - €120 = €30
• Divide by the old amount: €30 ÷ €120 = 0.25
• Multiply by 100 to get the percentage: 0.25 × 100 = 25%

So, your electricity bill has increased by 25%.

If you see a percentage increase on something like your rent or insurance, you can use this method to understand how much extra you're paying.

How to Calculate a Percentage Decrease?

A percentage decrease tells you how much something has reduced compared to its original value. This is useful when calculating discounts, sale prices, or cost reductions.

Formula for Percentage Decrease

Percentage Decrease = ((Old Value - New Value) ÷ Old Value) × 100

For example

A pair of runners originally cost €80, but they’re now on sale for €60.

• Find the difference in price: €80 - €60 = €20
• Divide by the original price: €20 ÷ €80 = 0.25
• Multiply by 100 to get the percentage: 0.25 × 100 = 25%

So, the runners are now 25% off.

When shopping, use this formula to quickly work out sale discounts and see if you're getting a good deal!

How Are Percentages Used in Everyday Life?

Percentages are useful in many daily situations. Here are some common examples:

Shopping Discounts

If a jacket is on sale for 25% off its original price of €200, you can calculate your savings like this:

• Multiply the discount percentage by the original price: 200 × 0.25 = 50
• New price: 200 - 50 = €150

Shops often use percentages to show discounts, so knowing how to calculate them helps you find the best deals!

Bank Savings & Interest Rates

If your bank offers 3% annual interest on a €1,000 savings account:

• Multiply the balance by the interest rate: 1000 × 0.03 = €30

So, at the end of the year, you’ll earn €30 in interest.

Health & Nutrition

If a 500g bottle of orange juice contains 10% sugar, how much sugar is in the entire bottle?

• Multiply the total weight by 0.10 (10%): 500 × 0.10 = 50g

So, the juice contains 50g of sugar.

How to Calculate Body Fat Percentage?

Your body fat percentage is the proportion of your total body weight that comes from fat. It is an important measure of fitness and overall health.

Formula for Body Fat Percentage

For men:
Body Fat % = (86.01 × log(Waist - Neck)) - (70.041 × log(Height)) + 36.76

For women:
Body Fat % = (163.205 × log(Waist + Hip - Neck)) - (97.684 × log(Height)) - 78.387

Example Calculation (for a man):

• Waist: 86cm
• Neck: 40cm
• Height: 175cm

Using the formula, the estimated body fat percentage is around 18%.

Good to know

Maintaining a healthy body fat percentage can improve heart health, energy levels, and fitness performance.

How to Calculate Weight Loss Percentage?

If you’re tracking your weight loss, using percentages helps measure progress effectively.

Formula for Weight Loss Percentage:

Weight Loss % = ((Starting Weight - Current Weight) ÷ Starting Weight) × 100

If you started at 80kg and now weigh 72kg:

• Find the weight lost: 80 - 72 = 8kg
• Divide by the starting weight: 8 ÷ 80 = 0.10
• Multiply by 100: 0.10 × 100 = 10%

So, you’ve lost 10% of your body weight! 

A 5-10% weight loss can reduce the risk of heart disease, diabetes, and other health issues.

How to Calculate a Percentage in Excel?

Excel makes percentage calculations quick and easy.

Example 1: Finding a Percentage of a Number

To calculate 25% of €200 in Excel:

• Type 200 in Cell A1
• Type 25% in Cell B1
• In Cell C1, enter the formula: =A1 * B1
• Press Enter, and it will return €50.

Example 2: Percentage Increase/Decrease

To calculate the percentage increase from €50 to €65:

• In Cell A1, enter 50 (old value)
• In Cell B1, enter 65 (new value)
• In Cell C1, type the formula: =((B1 - A1) ÷ A1) × 100
• Press Enter, and Excel will return 30%.

Use Excel’s % button to automatically format numbers as percentages.

How to Calculate Profit & Loss Percentage?

Businesses use percentages to calculate profits and losses.

Formula for Profit Percentage:

Profit % = (Profit ÷ Cost Price) × 100

Where:

• Profit = Selling Price - Cost Price

For example

A shop buys a product for €50 and sells it for €75.

• Find the profit: 75 - 50 = 25
• Divide by the cost price: 25 ÷ 50 = 0.50
• Multiply by 100: 0.50 × 100 = 50%

So, the shop made a 50% profit.

A loss percentage tells you how much money you lost compared to the original cost.

Formula for Loss Percentage

Loss % = (Loss ÷ Cost Price) × 100

Where:

• Loss = Cost Price - Selling Price

For example

You buy a concert ticket for €120, but at the last minute, you can’t go and have to sell it for €90.

• Find the loss: €120 - €90 = €30
• Divide by the cost price: €30 ÷ €120 = 0.25
• Multiply by 100: 0.25 × 100 = 25%

So, you’ve made a 25% loss. If you’re running a business and frequently experience losses, it might be time to adjust prices or reduce costs.

From tracking weight loss and calculating shopping discounts to working out savings interest and business profits, percentages are essential in everyday life.

Mastering simple percentage calculations helps you make better financial and health decisions. Need quick and accurate results? Try our instant percentage calculator today! 

Nishadh Mohammed

Nishadh Mohammed is a seasoned news editor and financial writer, working with HelloSafe since May 2023. Nishadh has developed expertise in financial markets, insurance, and investment products, with a deep understanding of the Canadian financial landscape. He has honed his SEO skills and content marketing strategies while writing for Canadian publishing houses. Armed with a master's in Business Analytics and extensive journalistic experience, Nishadh uniquely combines data proficiency and thorough research to deliver comprehensive and accessible information.