Boneyard Tools

Weighted Average Calculator

Find the weighted average of any set of numbers. Enter each value with its weight, such as grades and their percentages, to get the weighted mean.

How to calculate a weighted average

  1. Enter each value and the weight that applies to it.
  2. Add a row for every item you want to include.
  3. Read the weighted mean, total weight and weighted sum.

Examples

Two grades weighted 30 and 70 percent

90 at weight 30, 80 at weight 70
Weighted mean 83 (sum 8300 over weight 100)

Frequently asked questions

How do I calculate a weighted average?

Multiply each value by its weight, add those products to get the weighted sum, then divide by the total of the weights. For 90 at weight 30 and 80 at weight 70 the result is 8300 divided by 100, which is 83.

How is it different from a normal average?

A plain average treats every value equally. A weighted average lets some values count more, so a final exam worth 70 percent moves the result more than a quiz worth 30 percent.

Do the weights need to add up to 100?

No. Weights can be any non-negative numbers because the tool divides by their total. Weights of 30 and 70 give the same result as 3 and 7.

Can I use it for grades?

Yes. Enter each grade as the value and the category weight, such as homework, midterm and final, to get your weighted course grade.

What if the total weight is zero?

A weighted average needs a positive total weight, so the tool reports an error if every weight is zero. Give at least one item a weight above zero.

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