Formula Calculating Percentage

Percentage Calculator

1. Calculate X% of Y

Find a specific percentage of a given number.

2. Calculate What Percentage X is of Y

Determine what percentage one number is of another.

3. Calculate Percentage Change (Increase/Decrease)

Find the percentage increase or decrease between two values.

function calculatePercentOf() { var percentValue = parseFloat(document.getElementById('percentValue1').value); var totalAmount = parseFloat(document.getElementById('totalAmount1').value); var resultDiv = document.getElementById('result1'); if (isNaN(percentValue) || isNaN(totalAmount)) { resultDiv.innerHTML = 'Please enter valid numbers for both fields.'; resultDiv.style.backgroundColor = '#f8d7da'; resultDiv.style.borderColor = '#f5c6cb'; resultDiv.style.color = '#721c24'; return; } var result = (percentValue / 100) * totalAmount; resultDiv.innerHTML = percentValue + '% of ' + totalAmount + ' is: ' + result.toFixed(2) + ''; resultDiv.style.backgroundColor = '#e9f7ef'; resultDiv.style.borderColor = '#d4edda'; resultDiv.style.color = '#155724'; } function calculateWhatPercent() { var partValue = parseFloat(document.getElementById('partValue2').value); var wholeValue = parseFloat(document.getElementById('wholeValue2').value); var resultDiv = document.getElementById('result2'); if (isNaN(partValue) || isNaN(wholeValue)) { resultDiv.innerHTML = 'Please enter valid numbers for both fields.'; resultDiv.style.backgroundColor = '#f8d7da'; resultDiv.style.borderColor = '#f5c6cb'; resultDiv.style.color = '#721c24'; return; } if (wholeValue === 0) { resultDiv.innerHTML = 'The whole value cannot be zero.'; resultDiv.style.backgroundColor = '#f8d7da'; resultDiv.style.borderColor = '#f5c6cb'; resultDiv.style.color = '#721c24'; return; } var result = (partValue / wholeValue) * 100; resultDiv.innerHTML = partValue + ' is ' + result.toFixed(2) + '% of ' + wholeValue; resultDiv.style.backgroundColor = '#e9f7ef'; resultDiv.style.borderColor = '#d4edda'; resultDiv.style.color = '#155724'; } function calculatePercentChange() { var originalValue = parseFloat(document.getElementById('originalValue3').value); var newValue = parseFloat(document.getElementById('newValue3').value); var resultDiv = document.getElementById('result3'); if (isNaN(originalValue) || isNaN(newValue)) { resultDiv.innerHTML = 'Please enter valid numbers for both fields.'; resultDiv.style.backgroundColor = '#f8d7da'; resultDiv.style.borderColor = '#f5c6cb'; resultDiv.style.color = '#721c24'; return; } if (originalValue === 0) { resultDiv.innerHTML = 'The original value cannot be zero for percentage change.'; resultDiv.style.backgroundColor = '#f8d7da'; resultDiv.style.borderColor = '#f5c6cb'; resultDiv.style.color = '#721c24'; return; } var change = newValue – originalValue; var percentageChange = (change / originalValue) * 100; var type = (percentageChange >= 0) ? 'increase' : 'decrease'; resultDiv.innerHTML = 'Percentage ' + type + ': ' + Math.abs(percentageChange).toFixed(2) + '%'; resultDiv.style.backgroundColor = '#e9f7ef'; resultDiv.style.borderColor = '#d4edda'; resultDiv.style.color = '#155724'; }

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. A percentage is essentially a way of expressing a number as a fraction of 100. The word "percent" comes from the Latin "per centum," meaning "by the hundred."

What is a Percentage?

At its core, a percentage represents a part of a whole, where the whole is considered to be 100 units. For example, if you score 80% on a test, it means you got 80 out of every 100 possible points. The symbol '%' is used to denote a percentage.

Key Percentage Formulas

1. Calculating X% of Y

This formula helps you find a specific portion of a total amount. It's commonly used to calculate discounts, taxes, or commissions.

Formula: (Percentage / 100) * Total Amount

Example: What is 20% of 150?

• Percentage = 20
• Total Amount = 150
• Calculation: (20 / 100) * 150 = 0.20 * 150 = 30
• Result: 20% of 150 is 30.

Use the first section of our calculator above to quickly find X% of Y.

2. Calculating What Percentage X is of Y

This formula helps you determine what proportion one number represents of another, expressed as a percentage. This is useful for calculating grades, market share, or the proportion of a budget spent on a particular item.

Formula: (Part Value / Whole Value) * 100

Example: What percentage is 45 of 180?

• Part Value = 45
• Whole Value = 180
• Calculation: (45 / 180) * 100 = 0.25 * 100 = 25%
• Result: 45 is 25% of 180.

Input your values into the second section of the calculator to find out what percentage X is of Y.

3. Calculating Percentage Change (Increase or Decrease)

This formula is used to measure the relative change between an old value and a new value. It's crucial for analyzing growth, inflation, price changes, or performance improvements.

Formula: ((New Value - Original Value) / Original Value) * 100

Example 1: Percentage Increase
A product's price increased from 50 to 60. What is the percentage increase?

• Original Value = 50
• New Value = 60
• Calculation: ((60 – 50) / 50) * 100 = (10 / 50) * 100 = 0.20 * 100 = 20%
• Result: The price increased by 20%.

Example 2: Percentage Decrease
Sales dropped from 200 units to 150 units. What is the percentage decrease?

• Original Value = 200
• New Value = 150
• Calculation: ((150 – 200) / 200) * 100 = (-50 / 200) * 100 = -0.25 * 100 = -25%
• Result: Sales decreased by 25%. (The negative sign indicates a decrease).

Use the third section of the calculator to quickly determine percentage increases or decreases.

How to Use the Percentage Calculator

Our interactive calculator simplifies these common percentage calculations. Simply choose the type of calculation you need, enter the required numerical values into the respective input fields, and click the "Calculate" button. The result will be displayed instantly, helping you understand the percentages involved in your data.

Whether you're a student, a professional, or just managing your personal finances, mastering percentage calculations is an invaluable skill. This tool is designed to make that process straightforward and error-free.