Calculate a weighted mean from a list of values and their weights. Handy for grades, scores and any average where some items count more.
A weighted average lets some values count more than others. Each value is multiplied by its weight, the results are added up, and the total is divided by the sum of the weights. A course where the final exam is worth 50% is a classic example.
No. Weights can be any numbers, like 3, 2 and 1. The tool divides by the sum of the weights, so the scale does not matter. Percentages and fractions both work.
The plain average treats every value equally. The weighted average shifts toward the values with bigger weights, so the two match only when all weights are equal.