Use this calculator to determine the weighted average of a set of values. A weighted average is an average where some values contribute more than others to the final average. This is commonly used for calculating grades, financial portfolio returns, or survey results.
.calculator-container {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
background-color: #f9f9f9;
padding: 25px;
border-radius: 10px;
box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
max-width: 600px;
margin: 30px auto;
border: 1px solid #e0e0e0;
}
.calculator-container h2 {
text-align: center;
color: #333;
margin-bottom: 20px;
font-size: 1.8em;
}
.calculator-container p {
margin-bottom: 25px;
line-height: 1.6;
color: #555;
text-align: center;
}
.calc-input-group {
display: flex;
flex-wrap: wrap;
align-items: center;
margin-bottom: 15px;
background-color: #ffffff;
padding: 12px 15px;
border-radius: 8px;
border: 1px solid #e9e9e9;
}
.calc-input-group label {
flex: 1 1 40%;
color: #333;
font-weight: 600;
margin-bottom: 8px;
font-size: 0.95em;
}
.calc-input-group input[type="number"] {
flex: 1 1 55%;
padding: 10px 12px;
border: 1px solid #ccc;
border-radius: 5px;
font-size: 1em;
color: #333;
box-sizing: border-box;
margin-bottom: 8px;
}
.calc-input-group input[type="number"]:focus {
border-color: #007bff;
outline: none;
box-shadow: 0 0 0 2px rgba(0, 123, 255, 0.25);
}
.calculator-container button {
display: block;
width: 100%;
padding: 12px 20px;
background-color: #007bff;
color: white;
border: none;
border-radius: 5px;
font-size: 1.1em;
font-weight: 600;
cursor: pointer;
transition: background-color 0.3s ease, transform 0.2s ease;
margin-top: 20px;
}
.calculator-container button:hover {
background-color: #0056b3;
transform: translateY(-2px);
}
.calculator-container button:active {
transform: translateY(0);
}
.calc-result {
margin-top: 25px;
padding: 15px;
background-color: #eaf6ff;
border: 1px solid #b3e0ff;
border-radius: 8px;
font-size: 1.2em;
color: #0056b3;
text-align: center;
font-weight: 700;
min-height: 30px;
display: flex;
align-items: center;
justify-content: center;
}
@media (max-width: 480px) {
.calc-input-group label,
.calc-input-group input[type="number"] {
flex: 1 1 100%;
margin-bottom: 10px;
}
.calc-input-group {
padding: 10px;
}
}
function calculateWeightedAverage() {
var totalWeightedSum = 0;
var totalWeight = 0;
var validInputsFound = false;
for (var i = 1; i 0) {
totalWeightedSum += value * weight;
totalWeight += weight;
validInputsFound = true;
} else if ((!isNaN(value) && isNaN(weight)) || (isNaN(value) && !isNaN(weight))) {
// If one is a number and the other is not, it's an incomplete pair.
// We can choose to ignore it or show a specific warning. For now, ignore.
}
}
var resultDiv = document.getElementById("weightedAverageResult");
if (!validInputsFound) {
resultDiv.innerHTML = "Please enter at least one valid value and its corresponding positive weight.";
resultDiv.style.color = "#d9534f"; // Red for error
resultDiv.style.borderColor = "#d9534f";
return;
}
if (totalWeight === 0) {
resultDiv.innerHTML = "Error: Total weight cannot be zero. Please ensure weights are positive.";
resultDiv.style.color = "#d9534f"; // Red for error
resultDiv.style.borderColor = "#d9534f";
} else {
var weightedAverage = totalWeightedSum / totalWeight;
resultDiv.innerHTML = "Weighted Average: " + weightedAverage.toFixed(2);
resultDiv.style.color = "#0056b3"; // Blue for success
resultDiv.style.borderColor = "#b3e0ff";
}
}
Understanding the Weighted Average
A weighted average is a calculation that takes into account the varying degrees of importance (or "weight") of the numbers in a data set. Unlike a simple average where all numbers contribute equally, a weighted average assigns different weights to each number, reflecting its relative significance.
Why Use a Weighted Average?
The weighted average is a powerful tool used in many fields:
Academic Grades: Instructors often assign different weights to assignments, quizzes, midterms, and final exams. For example, a final exam might be worth 50% of your grade, while homework is only 20%.
Financial Portfolios: Investors use weighted averages to calculate the average return of a portfolio, where each asset's return is weighted by its proportion in the portfolio.
Survey Data: When collecting data from different demographic groups, researchers might weight responses to ensure the sample accurately reflects the population.
Economic Indicators: Indices like the Consumer Price Index (CPI) use weighted averages to reflect the impact of price changes on different categories of goods and services.
Imagine you're calculating your final grade in a course with the following components:
Homework: Score 85, Weight 20% (or 0.20)
Midterm Exam: Score 70, Weight 30% (or 0.30)
Final Exam: Score 92, Weight 50% (or 0.50)
Step 1: Multiply each value by its weight.
Homework: 85 × 0.20 = 17
Midterm: 70 × 0.30 = 21
Final Exam: 92 × 0.50 = 46
Step 2: Sum these products.
17 + 21 + 46 = 84
Step 3: Sum all the weights.
0.20 + 0.30 + 0.50 = 1.00 (or 20 + 30 + 50 = 100 if using percentages directly)
Step 4: Divide the sum of products by the sum of weights.
84 / 1.00 = 84
Your weighted average grade is 84.
Using the Calculator
Our Weighted Average Calculator simplifies this process. Simply enter the 'Value' for each item (e.g., a score, a percentage, a return) and its corresponding 'Weight' (e.g., percentage contribution, points, importance factor). The calculator will instantly provide you with the accurate weighted average, saving you time and reducing the chance of manual errors.
You can use either percentages (e.g., 20 for 20%) or decimal forms (e.g., 0.20) for weights, as long as you are consistent or understand that the calculator sums the raw weight numbers you input. If your weights sum to 100 (e.g., 20, 30, 50), the result will be correct. If they sum to 1 (e.g., 0.20, 0.30, 0.50), the result will also be correct.