Enter your values and their corresponding weights below to calculate the weighted average.
var pairCount = 4; // Initial number of pairs, matching the example
function addInputPair() {
pairCount++;
var inputPairsDiv = document.getElementById('inputPairs');
var newPairDiv = document.createElement('div');
newPairDiv.className = 'input-pair';
newPairDiv.innerHTML = `
`;
inputPairsDiv.appendChild(newPairDiv);
}
function calculateWeightedAverage() {
var sumOfProducts = 0;
var sumOfWeights = 0;
var resultDiv = document.getElementById('weightedAverageResult');
resultDiv.innerHTML = "; // Clear previous result
var allInputsValid = true; // Flag to check if all inputs are valid
for (var i = 1; i <= pairCount; i++) {
var valueInput = document.getElementById('value' + i);
var weightInput = document.getElementById('weight' + i);
// Check if the elements exist (important if pairs were dynamically added/removed, though not removed here)
if (!valueInput || !weightInput) {
continue;
}
var valueStr = valueInput.value.trim();
var weightStr = weightInput.value.trim();
// Only process if both value and weight are provided for a pair
if (valueStr !== "" && weightStr !== "") {
var value = parseFloat(valueStr);
var weight = parseFloat(weightStr);
if (isNaN(value) || isNaN(weight)) {
allInputsValid = false;
break; // Exit loop if any invalid number is found
}
sumOfProducts += (value * weight);
sumOfWeights += weight;
} else if (valueStr !== "" || weightStr !== "") {
// If one is filled and the other is not, it's an incomplete pair
allInputsValid = false;
break;
}
// If both are empty, just skip this pair (don't add to sums, don't mark as invalid)
}
if (!allInputsValid) {
resultDiv.innerHTML = 'Please ensure all entered values and weights are valid numbers, and that pairs are complete (both value and weight provided).';
return;
}
if (sumOfWeights === 0) {
resultDiv.innerHTML = 'The sum of weights cannot be zero. Please enter valid weights.';
return;
}
var weightedAverage = sumOfProducts / sumOfWeights;
resultDiv.innerHTML = 'The Weighted Average is: ' + weightedAverage.toFixed(4) + '';
}
.weighted-average-calculator-container {
background-color: #f9f9f9;
border: 1px solid #ddd;
padding: 20px;
border-radius: 8px;
max-width: 600px;
margin: 20px auto;
font-family: Arial, sans-serif;
}
.weighted-average-calculator-container h2 {
color: #333;
text-align: center;
margin-bottom: 20px;
}
.weighted-average-calculator-container p {
margin-bottom: 15px;
line-height: 1.6;
}
.input-pair {
display: flex;
flex-wrap: wrap;
align-items: center;
margin-bottom: 10px;
gap: 10px;
}
.input-pair label {
flex: 0 0 120px; /* Adjusted label width for better alignment */
font-weight: bold;
color: #555;
}
.input-pair input[type="number"] {
flex: 1 1 150px;
padding: 8px;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box;
}
.weighted-average-calculator-container button {
background-color: #007bff;
color: white;
padding: 10px 15px;
border: none;
border-radius: 5px;
cursor: pointer;
font-size: 16px;
margin-right: 10px;
margin-top: 15px;
}
.weighted-average-calculator-container button:hover {
background-color: #0056b3;
}
#weightedAverageResult {
margin-top: 20px;
padding: 10px;
background-color: #e9f7ef;
border: 1px solid #d4edda;
border-radius: 5px;
color: #155724;
text-align: center;
}
#weightedAverageResult p {
margin: 0;
font-size: 1.1em;
}
Understanding the Weighted Average
The weighted average is a type of average that takes into account the relative importance, or "weight," of each value in a dataset. Unlike a simple average where all values contribute equally, a weighted average assigns different levels of significance to each data point. This makes it a more accurate representation when certain values have a greater impact on the overall outcome.
When to Use a Weighted Average?
Weighted averages are commonly used in various fields:
Academic Grading: Different assignments (e.g., homework, quizzes, exams) often contribute different percentages to a final grade.
Financial Portfolios: Calculating the average return of a portfolio where different assets have different investment amounts.
Statistics and Data Analysis: When some data points are more reliable or representative than others.
Economic Indicators: Calculating average prices or indices where certain components have more influence.
The Weighted Average Formula
The formula for calculating a weighted average is:
Weighted Average = (Σ(X * W)) / ΣW
Where:
X represents each individual value.
W represents the weight assigned to each corresponding value.
Σ (Sigma) denotes the sum of.
In simpler terms, you multiply each value by its weight, sum up all these products, and then divide by the sum of all the weights.
How to Use the Calculator
Enter Values: In the "Value" fields, input the numbers for which you want to find the weighted average.
Enter Weights: In the "Weight" fields, input the corresponding weight for each value. Weights can be percentages (e.g., 0.25 for 25%), raw numbers, or any measure of importance.
Add More Pairs (Optional): If you have more than four value-weight pairs, click the "Add More Values" button to generate additional input fields.
Calculate: Click the "Calculate Weighted Average" button.
View Result: The calculated weighted average will be displayed below the button.
Example Calculation: Student's Final Grade
Let's say a student's final grade is determined by the following components:
Homework: 85% (Weight: 40% or 0.4)
Midterm Exam: 92% (Weight: 30% or 0.3)
Final Exam: 78% (Weight: 20% or 0.2)
Participation: 95% (Weight: 10% or 0.1)
Using the formula:
(85 * 0.4) = 34
(92 * 0.3) = 27.6
(78 * 0.2) = 15.6
(95 * 0.1) = 9.5
Sum of (X * W) = 34 + 27.6 + 15.6 + 9.5 = 86.7
Sum of Weights = 0.4 + 0.3 + 0.2 + 0.1 = 1.0
Weighted Average = 86.7 / 1.0 = 86.7
The student's weighted average grade is 86.7%.
You can input these values into the calculator to verify the result.