How to use Weighted Average Calculator
- Type one value and weight pair per line, separated by a comma, semicolon, tab or space.
- Choose how to read the second number: Weights or Percentages.
- Set the decimal places. The weighted average updates as you change the pairs.
- Check the total weight and each row's contribution in the table.
Example: Weighted Average Calculator
Average two test scores with different weights.
Options
- How to read the second number
- Weights uses the entries as the denominator. Percentages reads each second number as a share of 100 and reports what it did when they do not total 100.
- Value and weight pairs
- One pair per line, value first. Write decimals with a period and leave out thousands separators, so 1,000 becomes 1000.
- Decimal places
- 0, 2, 4, 6 or 8 for the printed result. The arithmetic keeps each number exact as a fraction, so a weight of 0.1 stays a tenth.
Supported inputs and limits
Where your input is processed
This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.
A weight is not a percentage by default
Weights of 1 and 3 mean the second value contributes three times as much as the first, and the denominator is 4. Percentage mode is labelled separately and reads each second number as a share of 100. If those entries total 90, the page reports that 90 became the denominator, so the total weight tells you which question was answered.
What weighted averages are used for
Course grades, portfolio returns and averages of averages all need weights, because some entries carry more of the whole. The contribution column shows how much of the final figure each row supplied, which quickly shows whether one entry dominates.
Questions about Weighted Average Calculator
How is this different from a plain average?
A plain average gives every value the same say. Here 80 at weight 1 and 90 at weight 3 gives (80 * 1 + 90 * 3) / 4 = 87.5, so the second value counts three times as much.
What happens when my percentages do not add up to 100?
The total you entered becomes the denominator and the result says so. Values 85, 90 and 70 at 30, 20 and 40 percent give 79.444444, a share of 90 rather than of 100.
Can a weight be zero?
Yes. The row stays in the table and adds nothing to the numerator or denominator, keeping an entry visible without changing the average.
Is the printed average rounded?
The arithmetic is exact and only the printed decimal is rounded, at the places you choose. An answer that repeats forever is marked as rounded.