Weighted Average Calculator

What is the Weighted Average Calculator?

A weighted average gives some values more influence than others. Instead of treating every number equally, each value is multiplied by its weight and the total is divided by the sum of the weights. It is the right average whenever items differ in importance or size.

Common uses include final marks when exams carry different weightage (for example 30% mid-term, 30% assignments and 40% final exam), CGPA with course credits, the average buying price of shares bought in several lots, and the average cost of stock held in inventory.

How to use the Weighted Average Calculator

1. Values (e.g. marks) — the numbers to average, separated by commas or spaces. (sample: 80, 72, 90)
2. Weights (same order, e.g. credits or %) — one weight per value, in the same order. (sample: 30, 30, 40)
3. Press Calculate Weighted Average (results also refresh as you type). The result card shows the Weighted Average, along with Sum of weights, Sum of value × weight and Simple (unweighted) average.

Formula used

Weighted average = Σ(xᵢ × wᵢ) ÷ Σwᵢ

• xᵢ = each value (mark, price, grade)
• wᵢ = the weight of that value (credits, % weightage, quantity)

The weights do not need to add up to 100 or 1 — the formula divides by their total, so weights of 3, 3 and 4 give the same answer as 30, 30 and 40.

Worked example

These are the sample values already filled in the calculator above, and the result it returns for them:

Tips for using the Weighted Average Calculator

• For an average share price, enter the purchase prices as values and the number of shares bought at each price as weights.
• If all the weights are equal, the weighted average equals the simple average.
• The weights must not add up to zero.