Weighted Average Calculator

How to Use the Weighted Average Calculator

Enter each value with its weight and this weighted average calculator (also a weighted mean calculator) shows the result, the simple average for comparison, how much each item contributes, and the working. Weights can be percentages or any positive numbers, so it handles weighted grades, average prices across purchases of different sizes, and any other data where some items count for more than others. You can type rows in or paste a list of values and weights straight from a spreadsheet.

Weighted Average Formula

Worked Examples

Values 80, 65 and 90 with weights 30, 20 and 50. The products are 80 × 30 = 2,400, 65 × 20 = 1,300 and 90 × 50 = 4,500, which add to 8,200. The weights add to 100, so the weighted average is 8,200 ÷ 100 = 82. The three items contribute 24, 13 and 45 points. The simple average is 78.33, so weighting lifts the result by 3.67 because the highest value carries the most weight.

Weighted average price: 100 units at $12 and 300 units at $10. The total cost is 100 × 12 + 300 × 10 = 4,200 for 400 units, so the weighted average price is 4,200 ÷ 400 = $10.50 per unit. The simple average of $12 and $10 is $11, which is wrong here because it ignores that three times as many units were bought at $10.

Reaching a target. With the first example, a new item worth a weight of 20 needs to score 100 to bring the average up to 85. To reach 90 it would need 130, which is impossible when 100 is the maximum, and the calculator flags that the best result would be 85.

Weighted Average vs Average

The ordinary average adds the values and divides by how many there are, so a one-hour task counts as much as a forty-hour one. The weighted average replaces “how many” with “how much each is worth”. Whenever the items are different sizes, or matter by different amounts, the simple average can be quite misleading, and the difference shown under the result tells you how far apart the two are.

Weighted Grades

For grades, enter each mark as a percentage and the assessment's share of the course as its weight. If you need help converting raw marks such as 43 out of 50 to percentages, or want to see which grade band you are in, use the grade percentage calculator. Course outlines and institutions differ in how they round and in their grade boundaries, so check yours.

Frequently Asked Questions

How do I calculate a weighted average?

Multiply each value by its weight, add up those products, then divide by the total of the weights. For values of 80, 65 and 90 with weights of 30, 20 and 50, the products are 2,400, 1,300 and 4,500, which total 8,200. Divide by the total weight of 100 and the weighted average is 82.

What is the weighted average formula?

Weighted average = Σ(value × weight) ÷ Σ(weight), where Σ means add up. This is also called the weighted mean. Because you divide by the total weight, the weights do not have to add up to 100: weights of 3, 2 and 5 give exactly the same answer as 30, 20 and 50.

What is the difference between a weighted average and a normal average?

A normal (simple) average counts every item equally, while a weighted average lets some items count for more. With the values 80, 65 and 90 the simple average is 78.33, but if the 90 is worth half the total the weighted average is 82. The two only match when every weight is equal.

How do I use a weighted grade calculator?

Enter each mark as the value and the assessment's share of the course as its weight, such as 80 with a weight of 30 for a 30% assignment. The result is your grade so far across the work you have completed. If you only have part of the course marked, tick the percentage option and the calculator will tell you how much of the weighting is still to come.

How do I calculate a weighted average price?

Use the quantity as the weight and the price as the value. If you buy 100 units at $12 and 300 units at $10, the total cost is 100 × $12 + 300 × $10 = $4,200 for 400 units, so the weighted average price is $4,200 ÷ 400 = $10.50 per unit. A simple average of the two prices would say $11, which overstates the cost because most of the units were the cheaper ones.

How do I calculate a weighted average in Excel?

In a spreadsheet, put the values in one column and the weights in another, use the SUMPRODUCT function on the two columns to get the sum of value × weight, then divide by the SUM of the weights column. Google Sheets and other spreadsheet programs use the same two functions. This calculator does the same job without any setup and also shows each item's contribution.

Do the weights have to add up to 100%?

No. The weights are divided by their own total, so any positive numbers work: units sold, credit points, hours or percentages. If you do use percentages and they add up to less than 100%, the result is the average of the work counted so far, and the calculator flags the gap. Weights above 100% in total are also accepted but flagged, because that is usually a typing mistake.

What is a weighted mean and when should I use it?

A weighted mean is another name for a weighted average. Use it when some data points matter more than others: course grades with different assessment weightings, an average cost across purchases of different sizes, survey groups of different sizes, or an investment portfolio return. If every item is equally important, the ordinary average is the right one.

What score do I need on my final to reach a target average?

Turn on the What value do I need? option, enter your target and the weight of the remaining item. If you hold 72 across the first 40% of a course and want 75 overall, the final worth the other 60% needs to score 77. If the answer is higher than the maximum possible, such as more than 100, the target cannot be reached and the calculator says so.