How to Calculate a Weighted Average
Use it when grades, prices, or measurements do not matter equally.
What it does and when to use it
An ordinary mean gives every value equal influence. A weighted average lets some items contribute more.
What information to enter
Enter each value and its weight. Weights may be credits, quantities, or percentages.
How to understand the result
The result is pulled toward values with larger weights.
Formula at a glance
Weighted average = sum(value × weight) ÷ sum(weights)
Short example
Scores 80, 90, and 100 with weights 1, 2, and 1 produce 90.
Common mistakes
- Adding weighted values without dividing by total weight.
- Mixing percentages and absolute weights inconsistently.
Perguntas frequentes
Must weights total 100?
No. They only need to be nonnegative and consistent.
How does this differ from a mean?
An ordinary mean gives every item a weight of 1.