Weighted Average Calculator
Enter each value with its weight and get the weighted average, the sum of the weights and the working written out in full: Σ(weight × value) ÷ Σ(weight). Use it for course grades, credit-weighted averages, survey groups of different sizes, or the average cost of a purchase made in lots. Free, no sign-up.
Values and Weights
Row 1
Row 2
Row 3
87.3333
Weighted average
60
Sum of weights
2
Rows counted
The working, step by step
Σ(w × x) = 20 × 92 + 40 × 85 = 1,840 + 3,400 = 5,240
Σw = 20 + 40 = 60
weighted average = 5,240 ÷ 60 = 87.3333
How to Use the Weighted Average Calculator
- 1. Enter the values and weights. Put each number in Value and how much it counts in Weight. The tool opens with two example rows, 92 with weight 20 and 85 with weight 40.
- 2. Add or remove rows. Add Row gives you another pair; Remove deletes a row (one row always stays). Blank rows are ignored.
- 3. Read the result. The weighted average, the sum of weights and the number of rows counted appear at once.
- 4. Check the working. Beneath the results the tool writes Σ(w × x), Σw and the final division with your numbers in them.
The Weighted Average Formula
Multiply each value by its weight, add the products, and divide by the sum of the weights: weighted average = Σ(wᵢ × xᵢ) ÷ Σwᵢ. Because you divide by the total weight, the weights do not need to add up to 100 or to 1 — percentages, credit hours, counts or decimals all give the same answer, as long as they are in proportion.
With the default rows, Σ(w × x) = 20 × 92 + 40 × 85 = 1840 + 3400 = 5240 and Σw = 60, so the weighted average is 5240 ÷ 60 = 87.3333. The ordinary average of 92 and 85 is 88.5; the weighted average is lower because the 85 carries twice the weight.
Worked Examples
| Situation | Values × weights | Result |
|---|---|---|
| Course grade: homework, exams | 92 × 20, 85 × 40 | 87.3333 |
| The same course with a project added | 92 × 20, 85 × 40, 78 × 30 | 84.2222, against a simple average of 85 |
| Grade points weighted by credit hours | 4.0 × 3, 3.3 × 4, 2.0 × 3 | 3.12 |
| Average price paid for 10 units at 50 and 20 units at 44 | 50 × 10, 44 × 20 | 46 |
| Mean score of three groups of different sizes | 72 × 25, 88 × 25, 95 × 50 | 87.5 |
What counts as a row
A row is used only when both boxes hold numbers and the weight is greater than zero. A row with a zero or negative weight, or with an empty box, is skipped, and the Rows counted figure shows how many were used. If you have finished only some of a course's categories, enter just those and their weights: you get your average on the work so far.
When to Use a Weighted Average
- Unequal importance. Exams that count for more than homework, or a final worth 40% of the grade.
- Unequal group sizes. A combined mean of classes or survey groups of different sizes weights each mean by its count.
- Credits and units. GPA weights grade points by credit hours; an average cost per unit weights each price by quantity.
- Not for everything. If every value counts equally, use the ordinary average. Check the grading scale and rounding rules of your institution before relying on a GPA figure.
Which Tool Do You Need?
| You want to… | Use |
|---|---|
| Average any values with any weights | This calculator |
| Work out a course grade from category weights and see what a final needs | Weighted Grade Calculator |
| Average test scores and find the next score needed | Test Average Calculator |
| Calculate a semester GPA on the 4.0 scale | GPA Calculator |
| Get the mean, median, mode and standard deviation of a data set | Statistics Calculator |
Frequently Asked Questions
- How is a weighted average calculated?
- Multiply each value by its weight, add the products, and divide by the sum of the weights. For 92 with weight 20 and 85 with weight 40, that is (1840 + 3400) ÷ 60 = 87.3333. The calculator writes out each of these steps with your numbers.
- Do my weights need to add up to 100 or 1?
- No. The formula divides by the total weight, so any consistent scale works — percentages, credit hours, counts or decimals. Weights of 20 and 40 give the same answer as 1 and 2.
- When should I use a weighted average instead of a regular average?
- Use one when some values matter more than others: course grades with category weights, GPA with credit hours, or survey groups of different sizes. A regular average treats every value equally.
- How do I use this for course grades?
- Enter each category's score as the value and its syllabus weight as the weight, such as homework 92 with weight 20 and exams 85 with weight 40. The result is your average across the categories entered. For a full grade breakdown and the score needed on a final, use the Weighted Grade Calculator.
- What happens to zero or negative weights?
- A row with a weight of zero or less is skipped, so a zero weight removes that value from the average and it is not counted in Rows counted. Negative weights are ignored rather than applied.
- How is a weighted average different from a weighted mean?
- They are the same thing. Weighted average is the everyday name and weighted mean the statistical one; both are Σ(w × x) ÷ Σw.