Weighted Average Calculator
Enter value and weight pairs to instantly compute a weighted average and total weight — runs 100% in your browser with nothing uploaded.
Weighted average: 90Total weight: 6Weighted std dev: 5Valid pairs: 3
🔒 Calculated in your browser — nothing is uploaded.
Weighted average from value and weight pairs
Enter one value, weight pair per line and the tool computes the weighted average live as you type. The weighted mean is defined as sum(value × weight) / sum(weight), so values with larger weights pull the result toward them more strongly than lightly weighted ones. Alongside the average you also see the weighted standard deviation — how tightly the values cluster around that weighted mean — the total weight, and how many valid pairs were parsed. Lines you leave blank, or that are missing a number, are quietly skipped — so you can paste a rough list from a spreadsheet and still get a clean answer.
Where a weighted average is useful
Weighted averages show up whenever some items count for more than others: a course grade where the final exam is worth more than a quiz, a GPA where each class is weighted by credit hours, an investment return weighted by the amount held in each position, or a survey score weighted by the number of respondents. Enter each item's value and its weight, and the calculator gives the single number that fairly summarizes the whole set. If every weight is the same, the weighted average is identical to the ordinary mean.
Frequently asked questions
How is the weighted average calculated?
It multiplies each value by its weight, adds those products together, and divides by the sum of the weights: sum(value × weight) / sum(weight). For example, 90 with weight 3 and 80 with weight 1 gives (90×3 + 80×1) / (3 + 1) = 350 / 4 = 87.5.
What happens if the total weight is zero or a line is malformed?
A total weight of zero has no defined average, so the tool shows a prompt instead of a number. Lines that are blank, missing the second number, or contain non-numeric text are ignored, and only the valid value/weight pairs are used.
What is the weighted standard deviation shown below the average?
It measures how spread out the values are around the weighted mean, giving each point its weight: sqrt(sum(weight × (value − mean)²) / sum(weight)). A result of 0 means every value is identical; a larger number means the values are more dispersed.
Is my data uploaded anywhere?
No. Every calculation runs locally in your browser with JavaScript — your numbers never leave your device and nothing is sent to a server.