Weighted Average Calculator
Combine values that matter by different amounts — course components, survey scores or portfolio returns — into a single weighted average.
Result
Enter your values and select Calculate to see the result.
How to use this calculator
- Enter each value and its weight. Add rows as needed.
- Weights can be percentages (20, 30, 50), decimals (0.2, 0.3, 0.5) or counts such as credits or quantities. They do not need to add up to 100.
- Weights cannot be negative, and at least one weight must be greater than zero.
Formula
weighted average = Σ(value × weight) ÷ Σ(weight)
Dividing by the total weight means the weights only need to be in the right proportion to each other.
Worked example
Course grade
Homework 92 (weight 20), midterm 78 (weight 30), final exam 85 (weight 50).
(92 × 20 + 78 × 30 + 85 × 50) ÷ (20 + 30 + 50) = 8,430 ÷ 100 = 84.3.
Assumptions and limitations
- If every weight is zero, a weighted average cannot be calculated and the calculator says so.
- Empty rows are skipped; partly filled rows are reported as errors.
Frequently asked questions
Do my weights need to add up to 100%?
No. The formula divides by the total weight, so weights of 1, 1 and 2 give the same result as 25%, 25% and 50%.
When is a weighted average better than a normal average?
Whenever some values should count more than others — for example exam components with different percentages, or prices bought in different quantities.