Weighted Average Calculator

How to use

1. 1Pick Table to enter rows by hand or Paste to drop in a column of label, value, weight lines from a spreadsheet.
2. 2Enter a value and a weight for each item. The label is optional. Weights can be percentages, counts, or any positive number.
3. 3Click a sample dataset like Course grade, Portfolio return, or Star rating to see how the calculation works.
4. 4Choose 2, 3, 4, or 6 decimal places so the result matches your grading policy, finance report, or scientific output.
5. 5Read the weighted average and the per-row share and contribution, then use Copy result for the headline or Copy summary for a full report.

About this tool

Weighted Average Calculator computes the weighted mean of any list of value and weight pairs. Build your list row by row in the table or paste a column of label, value, weight lines in the Paste mode; both modes feed the same calculation. The tool multiplies each value by its weight, sums the products, and divides by the sum of weights, which is the textbook weighted average formula and the same calculation behind a weighted course grade, a portfolio return, a weighted on-base percentage, an average customer rating from a star vote count, a weighted-by-quantity supplier price, or a survey response averaged by sample size. Weights can be percentages, raw counts, dollars, kilograms, or any positive number, and they do not need to sum to 100 or to 1; the formula normalizes them for you. The result panel shows the weighted average up top, the unweighted (plain) average for comparison, the total weight, the weighted sum, the item count, and the minimum and maximum values. The full breakdown table lists every row with its share of the total weight, its contribution to the weighted sum, and a horizontal bar that makes the influence of each row obvious at a glance, so the rows that dominate the result are easy to spot. Decimal precision is user-selectable at two, three, four, or six places to match school grading policies, finance reporting, or scientific work. Five built-in presets cover the most common searches in one click: course grade by syllabus weight, portfolio return by holding share, test score weighted by item count, supplier price weighted by purchased quantity, and product star rating from a 1 to 5 vote count. The Paste mode reads label, value, weight or just value, weight per line and tolerates commas, tabs, spaces, and semicolons as separators, so a column copied straight out of Excel, Google Sheets, or a CSV export drops in cleanly; comment lines starting with # are skipped, and the tool reports any skipped lines with a reason so a malformed row is easy to find and fix. A Copy result button copies just the headline weighted average, and a Copy summary button copies a clean text report (totals plus the per-row breakdown) ready to paste into a spreadsheet, an email, or a grade book. Everything runs locally in your browser using deterministic IEEE 754 arithmetic, so the grades, returns, and other numbers you paste here never leave your device.

Free to use. Works in your browser. No signup, no login.