This weighted average calculator computes an average where some values count more than others — course grades with different weights, investment returns, survey responses. Enter up to six value–weight pairs (weights can be percentages, credits, or any relative amounts).
What Is a Weighted Average?
A weighted average multiplies each value by its importance (its weight) before averaging: weighted average = Σ(value × weight) ÷ Σ(weights). A final exam worth 40% of a grade should move the average more than a homework assignment worth 5% — weights are how the average respects that. If all weights are equal, the weighted average collapses to the ordinary mean. This calculator is part of our Math Calculators collection.
Worked Example (Verified)
A course grade: exams average 85 (weight 40%), homework 92 (weight 20%), final exam 78 (weight 40%):
- Weighted sum: 85×40 + 92×20 + 78×40 = 3400 + 1840 + 3120 = 8360
- Total weight: 100 → weighted grade = 83.6
- The simple average (87) flatters the student — the heavy-weighted 78 pulls the true course grade down. That gap is exactly why weighted averages exist.
Where Weighted Averages Run the World
- GPA: grade points weighted by credit hours — computed purpose-built in our GPA Calculator.
- Investing: portfolio return is the weighted average of asset returns, weighted by position size; likewise the weighted average cost of shares after multiple buys.
- Grades & rubrics: categories weighted by importance — this calculator's home turf.
- Statistics: survey results re-weighted to match population demographics; expected value is a weighted average weighted by probabilities. For spread around such centers, see the Standard Deviation Calculator.
Using Weights That Do Not Sum to 100
No problem — the formula divides by the actual total weight, so weights of 4, 1 and 3 work exactly like 50%, 12.5% and 37.5%. Credit hours, point values, headcounts and dollar amounts are all valid weights. Just leave unused rows blank, and remember the one rule: a value with weight zero is excluded entirely.
Related Tools
- GPA Calculator — weighted averages for grades, purpose-built
- Standard Deviation Calculator
- Math Calculators — the full collection
Frequently Asked Questions
How do I calculate a weighted average?
Multiply each value by its weight, add those products, and divide by the sum of the weights: Σ(v×w) ÷ Σw.
Do the weights have to add up to 100?
No. Any weights work because the formula normalizes by their total. Percentages that sum to 100 are just the most familiar case.
What is the difference between weighted and simple average?
A simple average treats every value equally. A weighted average lets important values count more — that is the only difference, and it matters whenever values are not equally important.
How do I calculate my final grade with weights?
Enter each category score as a value and its percentage of the course as the weight — like the worked example: 85 @ 40, 92 @ 20, 78 @ 40 → 83.6.
Can a weight be negative or zero?
Zero simply excludes the value. Negative weights are mathematically possible but almost never meaningful for grades and scores; this calculator treats any row with weight 0 or blank as unused.
Is this weighted average calculator free?
Yes — free, instant, no sign-up.