Weighted Average Calculator
Free weighted average calculator — combine values with their weights in one step. Great for grades, GPAs and any weighted score. Works in your browser.
Type your values (e.g. test scores) and their weights (e.g. 0.2 for 20%) as two comma-separated lists in the same order. The calculator returns the combined weighted average.
The formula
weighted average = (Σ valueᵢ × weightᵢ) ÷ (Σ weightᵢ)
Multiply each value by its weight, sum those products, and divide by the total of the weights.
Worked example: a class grade
| Component | Score | Weight |
|---|---|---|
| Homework | 85 | 20% |
| Midterm | 92 | 50% |
| Final | 78 | 30% |
(85 × 0.2) + (92 × 0.5) + (78 × 0.3) = 17 + 46 + 23.4 = 86.4
The weights don’t have to add up to 1 or to 100 — only their ratio matters. Weights of 1, 2, 1 give the same answer as 25%, 50%, 25%.
Common uses
- Class grades and GPAs (a 4-credit course pulls more than a 1-credit one)
- Portfolio returns (each holding weighted by its share of the portfolio)
- Survey scores (some questions weighted more heavily)
- Sports stats (e.g. slugging percentage weights hits by total bases)
Decimal separator
Use the dot for decimals (0.2) so commas can separate the list items.
Whitespace and semicolons also work as separators.
Worked examples
-
Homework 85 (20%), midterm 92 (50%), final 78 (30%)
Weighted average: 86.4
-
Same with integer weights (1, 2, 1) on 80, 90, 70
Weighted average: 82.5
Frequently asked questions
What's the formula for a weighted average?
(value₁ × weight₁ + value₂ × weight₂ + …) ÷ (weight₁ + weight₂ + …). Multiply each value by its weight, sum those products, divide by the sum of the weights.
Do the weights need to add up to 100, or to 1?
Neither — only the *relative* weights matter. "Worth 1 vs 2" gives the same answer as "worth 33% vs 67%". The formula divides by the total weight, so the scale cancels out.
How is this different from a plain average?
A plain (arithmetic) average treats every value equally. A weighted average gives some values more pull than others — useful when items don't count equally (a final exam vs a quiz, a large investment vs a small one).
How do I write decimals?
Use the dot as the decimal point (0.2, not 0,2). The comma is used to separate items in the list. Spaces and semicolons also work as separators.
What if a weight is zero?
Items with weight zero have no effect on the answer — they're effectively skipped. If *all* weights are zero, there's no weighted average to compute (the formula divides by zero) and we return an error.
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