Weighted Average Calculator
Weighted Average Calculator
Enter a list of values and a matching list of weights (in the same order). This calculates the weighted average — where each value contributes to the result in proportion to its weight, rather than counting equally like a simple average.
Weighted averages show up whenever some data points should count more than others: a course grade where the final exam is worth more than a homework assignment, a portfolio return where larger holdings should influence the result more than smaller ones, or a product rating that weights recent reviews more heavily. The weights don't need to sum to 1 or 100 — the formula automatically normalizes by dividing by the total of all weights, so you can enter them as percentages, raw counts, or any consistent scale.
- Formula: Weighted Average = Σ(Value × Weight) ÷ Σ(Weight) — each value is multiplied by its weight, summed, then divided by the total of all weights.
- Weights don't need to sum to 1: the formula automatically normalizes by dividing by the total weight, so you can enter weights as percentages (50, 30, 20) or decimals (0.5, 0.3, 0.2) — both give the same result.
- Common use case — course grades: if your final grade is 50% exam, 30% homework, and 20% participation, enter your scores in each category as values and those percentages as weights.
What if I just want a regular (unweighted) average?
Give every value an equal weight (like 1 for each) — this makes the weighted average formula produce the same result as a plain mean.
Do the values and weights lists need to be the same length?
Yes — each value needs a matching weight in the same position; if the lists are different lengths, only the overlapping pairs (up to the shorter list's length) are used.
Weighted Average Calculator
Enter a list of values and a matching list of weights (in the same order). This calculates the weighted average — where each value contributes to the result in proportion to its weight, rather than counting equally like a simple average.
Weighted averages show up whenever some data points should count more than others: a course grade where the final exam is worth more than a homework assignment, a portfolio return where larger holdings should influence the result more than smaller ones, or a product rating that weights recent reviews more heavily. The weights don't need to sum to 1 or 100 — the formula automatically normalizes by dividing by the total of all weights, so you can enter them as percentages, raw counts, or any consistent scale.
- Formula: Weighted Average = Σ(Value × Weight) ÷ Σ(Weight) — each value is multiplied by its weight, summed, then divided by the total of all weights.
- Weights don't need to sum to 1: the formula automatically normalizes by dividing by the total weight, so you can enter weights as percentages (50, 30, 20) or decimals (0.5, 0.3, 0.2) — both give the same result.
- Common use case — course grades: if your final grade is 50% exam, 30% homework, and 20% participation, enter your scores in each category as values and those percentages as weights.
What if I just want a regular (unweighted) average?
Give every value an equal weight (like 1 for each) — this makes the weighted average formula produce the same result as a plain mean.
Do the values and weights lists need to be the same length?
Yes — each value needs a matching weight in the same position; if the lists are different lengths, only the overlapping pairs (up to the shorter list's length) are used.