How is a weighted average calculated?

Multiply each value by its weight, add those products together, then divide by the sum of the weights: Σ(value × weight) ÷ Σ(weight).

Do the weights have to add up to 100 or 1?

No. Weights can be any numbers — they are normalised automatically by dividing by their total, so weights of 3, 2, 1 work the same as 50%, 33%, 17%.

Is anything sent to a server?

No — the calculation happens entirely in your browser and no data leaves your device.

Weighted Average Calculator

Weighted average calculator

A weighted average gives some values more influence than others. Instead of treating every number equally, each value is multiplied by a weight before being combined:

weighted average = Σ(value × weight) ÷ Σ(weight)

This is how course grades work when an exam counts for more than a quiz, or how a portfolio return blends holdings of different sizes. Weights do not need to sum to 1 or 100 — they are normalised by their total automatically. Add as many rows as you need; the result is computed live in your browser.