How to Calculate Amount in Percentage

Percentage Calculator

What Percentage is X of Y?

Find what percentage one number is of another.

The percentage is: 20.00%

What is X% of Y?

Find a specific percentage of a given number.

The part value is: 50.00

function calculatePercentage() { var partValue = parseFloat(document.getElementById("partValue").value); var wholeValue = parseFloat(document.getElementById("wholeValue").value); var resultElement = document.getElementById("percentageResult"); if (isNaN(partValue) || isNaN(wholeValue)) { resultElement.innerHTML = "Please enter valid numbers for both fields."; resultElement.style.backgroundColor = '#f8d7da'; resultElement.style.borderColor = '#f5c6cb'; resultElement.style.color = '#721c24'; return; } if (wholeValue === 0) { resultElement.innerHTML = "The whole value cannot be zero."; resultElement.style.backgroundColor = '#f8d7da'; resultElement.style.borderColor = '#f5c6cb'; resultElement.style.color = '#721c24'; return; } var percentage = (partValue / wholeValue) * 100; resultElement.innerHTML = "The percentage is: " + percentage.toFixed(2) + "%"; resultElement.style.backgroundColor = '#e9f7ef'; resultElement.style.borderColor = '#d4edda'; resultElement.style.color = '#155724'; } function calculatePartOfNumber() { var percentageValue = parseFloat(document.getElementById("percentageValue").value); var wholeValueForPart = parseFloat(document.getElementById("wholeValueForPart").value); var resultElement = document.getElementById("partResult"); if (isNaN(percentageValue) || isNaN(wholeValueForPart)) { resultElement.innerHTML = "Please enter valid numbers for both fields."; resultElement.style.backgroundColor = '#f8d7da'; resultElement.style.borderColor = '#f5c6cb'; resultElement.style.color = '#721c24'; return; } var part = (percentageValue / 100) * wholeValueForPart; resultElement.innerHTML = "The part value is: " + part.toFixed(2); resultElement.style.backgroundColor = '#e9f7ef'; resultElement.style.borderColor = '#d4edda'; resultElement.style.color = '#155724'; } // Initial calculations on page load to show default values window.onload = function() { calculatePercentage(); calculatePartOfNumber(); };

Understanding and Calculating Percentages

Percentages are a fundamental concept in mathematics, used widely in everyday life, from finance and statistics to shopping discounts and academic grades. The word "percent" comes from the Latin "per centum," meaning "by the hundred." Essentially, a percentage is a way of expressing a number as a fraction of 100.

What is a Percentage?

A percentage is a dimensionless number (ratio) expressed as a fraction of 100. It is denoted by the percent sign (%). For example, 50% means 50 out of 100, or 50/100, which simplifies to 1/2 or 0.5 as a decimal. Percentages are useful for comparing quantities and understanding proportions in a standardized way.

How to Calculate Percentage (Part of a Whole)

One of the most common percentage calculations is determining what percentage one number (the part) is of another number (the whole). This is often used to calculate scores, success rates, or proportions.

The formula for this calculation is:

Percentage = (Part Value / Whole Value) × 100

Example:

Suppose you scored 85 marks out of a total of 120 marks in an exam. To find your percentage score:

• Part Value = 85
• Whole Value = 120
• Percentage = (85 / 120) × 100 = 0.70833… × 100 ≈ 70.83%

So, you scored approximately 70.83% in the exam.

How to Calculate a Part (Percentage of a Number)

Another common scenario is when you know the total amount and a percentage, and you want to find out what that percentage represents in terms of the actual value. This is useful for calculating discounts, taxes, or portions of a budget.

The formula for this calculation is:

Part Value = (Percentage / 100) × Whole Value

Example:

Imagine a store is offering a 15% discount on an item that originally costs 80 units. To find the discount amount:

• Percentage = 15
• Whole Value = 80
• Part Value = (15 / 100) × 80 = 0.15 × 80 = 12

The discount amount is 12 units. So, the item would cost 80 – 12 = 68 units after the discount.

Why are Percentages Important?

Percentages provide a standardized way to express proportions, making it easier to compare different quantities even if their original "wholes" are different. For instance, comparing a 70% score on a 100-point test to a 70% score on a 50-point test immediately tells you the relative performance, regardless of the total points available. They simplify complex ratios into an easily understandable format, which is crucial for decision-making in various fields.

Use the calculator above to quickly perform these common percentage calculations!