Online weighted average calculator. Enter the values and their percentage weights to compute the weighted average and learn the formula behind it. Use a period as the decimal separator. Remove or leave blank any boxes you do not use.
Weighted Average =
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Enter each value with its percentage and press Calculate. The result box shows the weighted average.
If we define each value as Vi and its respective weight as Wi, then the formula for the weighted average (also known as the weighted mean) is as follows:
In this formula, Vi represents the individual values to be averaged, and Wi are the weights assigned to each value: a percentage, a count, hours, or any other positive number. The numerator calculates the weighted sum of all values, and the denominator calculates the sum of all weights. Dividing the numerator by the denominator gives the weighted average.
This calculator does compute a weighted average without percentages. The % next to each weight is only a label: you can type credits, hours, frequencies, or any positive number. They do not need to add to 100; the calculation divides by the sum of the weights you entered.
With the same values 65, 70, 43 and 54, the weights 1, 2, 3 and 4 give (65 × 1 + 70 × 2 + 43 × 3 + 54 × 4) / 10 = 55. That is the same result as 10%, 20%, 30% and 40%, because the ratio between weights is identical.
You can do the same in Excel, and below we show both ways: a simple average (equal weights) with AVERAGE, and a weighted average (unequal weights, % or any other number) with SUMPRODUCT divided by SUM.
When every value counts equally, one column is enough. Enter 65, 70, 43 and 54 in A2:A5 and, in another cell, =AVERAGE(A2:A5). Excel adds them and divides by the count: the result is 58. Written out, that is the same as =SUM(A2:A5)/COUNT(A2:A5).
If the values have different weights, use two columns: the values in A2:A5 and the weights 10, 20, 30 and 40 in B2:B5. In another cell enter =SUMPRODUCT(A2:A5, B2:B5)/SUM(B2:B5). SUMPRODUCT multiplies each value by its weight and adds the products; SUM divides by the total of the weights, even if they do not add to 100. With that data the result is 55. Keep the same format down column B: do not mix 10 and 10%.
A simple average (the arithmetic mean) treats every value the same: add them up and divide by how many there are. For 65, 70, 43 and 54, the mean is (65 + 70 + 43 + 54) / 4 = 58. Order does not matter; each value counts equally.
A weighted average is used when the items do not count equally. Multiply each value by its weight (%), add those products, and divide by the total of the weights. With the same values at 10%, 20%, 30% and 40%: (65 × 10 + 70 × 20 + 43 × 30 + 54 × 40) / 100 = 55. The 54 weighs more than the 65, so the average drops. When every weight is equal, both methods give the same result.