Weighted average calculator
Work out a grade average with weights — enter the marks and their weights, and the calculator shows the weighted average alongside the plain arithmetic mean.
The weighted average of 3 marks is 3.83, while the plain mean is 4.00.
Formula
oᵢ is each mark and wᵢ its weight. Multiply each mark by its weight, add them up and divide by the total of the weights.
How we got there
When all the weights are equal, the weighted average is identical to the arithmetic mean.
How to work out a weighted average by hand
- Multiply each mark by its weight
A mark of 5 with weight 2 gives 10, a 4 with weight 1 gives 4, and a 3 with weight 3 gives 9.
- Add the results
10 + 4 + 9 = 23. That is the numerator.
- Add the weights
2 + 1 + 3 = 6. That is the denominator.
- Divide
23 ÷ 6 = 3.83. That is the weighted average. The plain mean of those marks is 4.00 — the weights change the answer.
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Frequently asked questions
In an arithmetic mean every mark counts the same. In a weighted mean each carries a weight — a test counts for more than a quiz.
It depends on the school and the teacher — commonly a test 3, a quiz 2 and classwork 1. Enter your own weights in the calculator.
For a reported grade usually yes, but the rounding rule is the school’s. The calculator gives the exact figure to two decimal places.
A mark with weight 0 has no effect. The calculator leaves it out of both the numerator and the total of the weights.
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