About the Weighted Average Calculator
This weighted average calculator finds the mean of a set of values when some values matter more than others. Enter the values in one box and their weights in the other — in the same order — and it returns the weighted average, the total weight, each item’s share of the total weight and how much it contributes to the result.
Common uses include working out a course grade where homework, quizzes and exams carry different percentages, a GPA weighted by credit hours, the average price paid across several purchases of different sizes, a portfolio’s average return weighted by the money in each holding, and weighted scoring for decisions. The simple (unweighted) average is shown too, so you can see how much the weighting changes the answer.
Values may be negative (such as a losing investment’s return); weights can be percentages, credit hours, quantities or any positive numbers — they do not need to add up to 100, because the calculator divides by their total. If the two lists have different lengths, only matching pairs are used and you are told how many were ignored.
With the default inputs, the weighted average is 83.9. Change any value above to recalculate instantly.
How to use the weighted average calculator
- 1Type the values you want to average, separated by commas or new lines.
- 2Type the matching weights in the same order.
- 3Read the weighted average and compare it with the simple average.
- 4Check the breakdown table to see each item’s share of the weight and its contribution.
Formula and method
Multiply each value by its weight, add up those products, and divide by the sum of the weights. Dividing by the total weight means the weights do not have to add up to 1 or 100 — weights of 2, 3 and 5 give exactly the same result as 20%, 30% and 50%.
Each item’s contribution is wᵢ × xᵢ ÷ Σwᵢ; the contributions add up to the weighted average. When every weight is equal, the formula reduces to the ordinary arithmetic mean. For a course grade, use the category percentages as weights and your average score in each category as the values.
- x̄w
- Weighted average
- xᵢ
- Each value (score, price, return…)
- wᵢ
- Weight of each value (percentage, credits, quantity…)
Worked examples
Course grade by category
Homework 92 (20%), quizzes 85 (30%), final exam 78 (40%) and project 88 (10%): 92×20 + 85×30 + 78×40 + 88×10 = 8,390, divided by 100 gives 83.9. The heavy, lower exam score pulls it below the simple average of 85.75.
GPA weighted by credit hours
Grade points × credits = 10.5 + 15.2 + 5.8 = 31.5 over 9 credits, so the weighted GPA is 3.5 — higher than the simple 3.4 because the 4-credit course had the best grade.
Average price across three purchases
Buying 100 units at $45, 250 at $52 and 150 at $49 costs $24,850 for 500 units, an average of $49.70 per unit — the true average cost, unlike the simple average of $48.67.
Portfolio return with a losing holding
Holdings of $50,000 returning 12%, $30,000 returning −8% and $20,000 returning 5%: 600,000 − 240,000 + 100,000 = 460,000, divided by $100,000 gives a 4.6% portfolio return. The losing holding contributes −2.4 points and shows as a bar below zero.
Frequently asked questions
How do you calculate a weighted average?+
Multiply each value by its weight, add the products together, then divide by the total of the weights. For scores of 80 (weight 1) and 90 (weight 3): (80 + 270) ÷ 4 = 87.5.
Do the weights have to add up to 100%?+
No. Because the formula divides by the sum of the weights, any positive weights work. Weights of 1, 1 and 2 give the same answer as 25%, 25% and 50%.
What is the difference between an average and a weighted average?+
A simple average treats every value equally. A weighted average lets some values count more — for example a final exam worth 40% of a grade — so it better reflects their real importance or size.
How do I calculate my weighted grade if some categories are not graded yet?+
Enter only the categories you have scores for, with their weights. The calculator divides by the weights you entered, giving your current standing; use the final grade calculator to see what you need on the rest.
Can weights be negative?+
In normal weighted averages, no — weights represent importance, size or frequency and should be zero or positive. Negative weights can produce results outside the range of your values, so the calculator warns you if it sees one.