All calculators

Weighted Average Calculator

Enter your values and a matching list of weights. The weighted average appears with the plain average beside it, so you can see what the weighting changed.

Your values and weights

The figures being averaged — grades, scores, prices, rates.
How much each value counts, in the same order. Credit hours, quantities, percentages.
Working
(4 × 4 + 3 × 4 + 4 × 3 + 2.3 × 2) ÷ 13
Pairs
4, 3, 4, 2.3 weighted by 4, 4, 3, 2
Weighted average
3.4308
Unweighted average
3.325
Total weight
13
Sum of value × weight
44.6
How many pairs
4
Weighting effect
+0.1058

How to use this calculator

  1. Enter your values in the first box — grades, prices, scores, rates.
  2. Enter the weights in the second box, in the same order. The third weight belongs to the third value.
  3. Read the weighted average, then compare it with the unweighted one beside it. The gap between them is what the weighting is doing.

Both boxes take commas, spaces or new lines, so two columns copied out of a spreadsheet can be pasted straight in.

How to calculate a weighted average

Each value is counted as many times as its weight says, and the total is divided by the number of counts rather than the number of values.

Weighted mean = Σ(w × x) ÷ Σw
  • x — each value, e.g. a grade of 4.0
  • w — its weight, e.g. 4 credit hours
  • Σ — "the sum of", added across every pair

When every weight is the same, the weights cancel out and the result is the ordinary mean. That is worth knowing: the plain average is just a weighted average where nothing counts for more than anything else.

A worked example: grade point average

Four courses, weighted by credit hours
CourseGradeCredits
Statistics4.04
Economics3.04
History4.03
Chemistry2.32

The products are 4.0 × 4 = 16, 3.0 × 4 = 12,4.0 × 3 = 12 and 2.3 × 2 = 4.6, which add to 44.6. The credits add to 13, so the GPA is 44.6 ÷ 13 = 3.43.

Averaging the four grades without weights gives 3.325. The weighted figure is higher because the weakest grade came from the smallest course — which is exactly the distinction a GPA exists to make.

Frequently asked questions

How do I calculate a weighted average?

Multiply each value by its weight, add those products, then divide by the total weight. For grades 4.0, 3.0, 4.0 and 2.3 with credit weights 4, 4, 3 and 2, the products total 44.6 and the weights total 13, giving 3.43.

How is it different from an ordinary average?

An ordinary average treats every value as equally important. A weighted average lets some count for more. The same four grades average 3.325 unweighted but 3.43 weighted, because the 4.0s carry more credits than the 2.3 does.

What should I use as weights?

Whatever measures how much each value counts: credit hours for a GPA, quantities for an average price, assessment percentages for a course mark, or population sizes when combining regional figures. Weights do not need to add up to 100 or to anything in particular.

Can weights be decimals or percentages?

Yes. Weights of 40, 35 and 25 behave exactly like 0.4, 0.35 and 0.25, because only their relative sizes matter. The division by the total weight cancels any common scale.

Why does it say the lists do not match?

Because there are more values than weights, or the other way round. Each value needs exactly one weight, paired by position, so the first value goes with the first weight. The message shows both counts so you can see which list is short.

Can a weight be zero or negative?

A zero weight is fine — it simply drops that value out of the average. Negative weights are accepted but rarely mean anything; if the weights sum to zero the calculation has no answer, and the calculator says so instead of dividing by zero.