Weighted Average Calculator
This weighted average calculator finds the mean of a set of values when each one counts differently. Enter one value and its weight per line and the result updates instantly, along with the number of values and the total weight. It is perfect for grades where each exam or assignment is worth a different percentage, for grade point averages (GPA), for scoring surveys, or for any situation where some numbers should count more than others.
One pair per line: value and weight (separated by a space, comma or colon).
Weighted average
Number of values
Sum of weights
Each value is multiplied by its weight, the products are added and the total is divided by the sum of the weights. If a weight is missing, it is taken as 1.
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How it works
A weighted average multiplies each value by its weight, adds up all those products, and divides the total by the sum of the weights. So for grades 8, 6 and 9 with weights 3, 2 and 4, you compute (8×3 + 6×2 + 9×4) ÷ (3+2+4) = 72 ÷ 9 = 8. When every weight is the same, the weighted average is identical to a plain arithmetic mean; the weights only matter when they differ.
Worked example: a term grade
Suppose a course grades a first midterm worth 30%, a second midterm worth 30% and a final exam worth 40%. A student scores 7, 8 and 6 respectively. The weighted average multiplies each grade by its weight, adds the products and divides by the sum of the weights: (7×30 + 8×30 + 6×40) ÷ 100 = 690 ÷ 100 = 6.9. Because the final carries the most weight, the lower score of 6 pulls the average down more than either midterm would.
| Assessment | Grade | Weight | Contribution (grade×weight) |
|---|---|---|---|
| First midterm | 7 | 30% | 2.10 |
| Second midterm | 8 | 30% | 2.40 |
| Final exam | 6 | 40% | 2.40 |
| Total | — | 100% | 6.90 |
Simple mean vs weighted average
With the same three grades — 7, 8 and 6 — a simple arithmetic mean treats them equally and returns (7 + 8 + 6) ÷ 3 = 7.0. The weighted average gives the final exam more influence, so the same numbers yield 6.9 instead. The gap looks small here, but it grows as the weights become more uneven. This is why courses that weight a final heavily can produce a term grade noticeably different from a plain average of all the scores.
| Method | Calculation | Result |
|---|---|---|
| Simple mean | (7 + 8 + 6) ÷ 3 | 7.0 |
| Weighted average | (7×30 + 8×30 + 6×40) ÷ 100 | 6.9 |
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Preguntas frecuentes
- What is a weighted average?
- A weighted average is a mean in which each value contributes according to a weight instead of counting equally. Values with larger weights pull the result toward them. It is computed by multiplying every value by its weight, summing those products, and dividing by the sum of the weights.
- How do I calculate my grade with weighted percentages?
- Enter each grade followed by its percentage or weight, one pair per line. For example, an exam of 8 worth 50%, a project of 6 worth 20% and homework of 9 worth 30% would be "8 50", "6 20", "9 30". The calculator returns (8×50 + 6×20 + 9×30) ÷ 100 = 7.9.
- What if I do not enter a weight for a value?
- If a line has only a value and no weight, the calculator treats its weight as 1. That way you can mix weighted and unweighted entries, and if every line has no weight the result is just the ordinary arithmetic mean.
- Do the weights have to add up to 100?
- No. The weights can be any positive numbers — percentages, credits, hours or arbitrary points. Because the calculator divides by the total weight, only the ratios between the weights matter, not their sum. Weights of 3, 2, 4 give the same result as 30, 20, 40.
- What is the difference between a weighted average and a normal average?
- A normal (arithmetic) average treats every value equally, as if all weights were 1. A weighted average lets some values count more than others. When all the weights are equal the two are identical; they only differ once the weights vary.