What is a weighted average?

A weighted average assigns a relative importance (weight) to each value before averaging. The result is: sum(value × weight) / sum(weights). When all weights are equal, it equals a simple arithmetic mean.

Do weights need to add up to 100?

No. Weights can be any positive numbers — percentages (summing to 100), fractions, or counts. The calculator normalizes them automatically when computing the result.

Can I use negative values?

Values can be negative (e.g., returns of −5%). Weights must be positive numbers; a zero or negative weight is not meaningful and will be flagged as invalid.

What happens if all weights are zero?

The weighted average is undefined when the total weight is zero. The calculator will show an error and ask you to enter at least one positive weight.

How is this different from a simple average?

A simple average treats every value equally. A weighted average lets some values contribute more to the result — for example, a final exam worth 40% of a grade matters more than a quiz worth 10%.

Weighted Average Calculator

Name: Weighted Average Calculator
Availability: InStock
Author: Nham Vu

Enter values and their weights to instantly calculate the weighted average (weighted mean).

Values & Weights

Label (optional)

Value

Weight

Result

Weighted Average

—

Sum of Products

—

Total Weight

—

Rows

Simple Average

—

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Summary

Enter values and their weights to instantly calculate the weighted average (weighted mean).

How it works

Enter a value and its weight in the first row.
Click "Add Row" to include more value-weight pairs.
Adjust any value or weight — the result updates automatically.
The weighted average is calculated as the sum of (value × weight) divided by the sum of all weights.
Click "Reset" to clear all rows and start over.

Use cases

Calculate a final course grade from assignments with different credit weightings.
Compute a portfolio return weighted by asset allocation percentages.
Analyze survey results where respondents represent groups of different sizes.
Average product ratings weighted by the number of reviews per source.
Determine weighted cost of capital (WACC) in corporate finance.
Compute a weighted GPA across courses with varying credit hours.
Average sensor readings weighted by measurement confidence.
Price index calculations in economics and market research.

Frequently Asked Questions

Last updated: 2026-06-10 · Reviewed by Nham Vu