BYTETOOLS

Weighted Average Calculator

Compute a weighted average from value and weight pairs: Σ(value × weight) ÷ Σ(weights). Add rows for grades, portfolios or ratings and see each weight's share.

ValueWeightShare
20%
30%
50%
78
Weighted average

Details

7,800
Σ (value × weight)
100
Σ weights
80
Unweighted mean

Weighted average = Σ(value × weight) ÷ Σ(weight). Weights are normalised automatically, so they do not need to add up to 100.

What is the Weighted Average Calculator?

The ByteTools Weighted Average Calculator computes the weighted mean of any set of numbers: multiply each value by its weight, add them up and divide by the total weight — Σ(value × weight) / Σ(weight).

  • Unlimited value/weight rows with add and remove
  • Shows the weighted sum, total weight and plain average for comparison
  • Normalised weight percentage per row
  • Weights can be any positive numbers — no need to total 100
  • Instant recalculation as you type
  • 100% private — nothing is uploaded

How to use the Weighted Average Calculator

  1. 1

    Enter each value and its weight in a row.

  2. 2

    Click Add row for more entries, or the remove button to delete one.

  3. 3

    Read the weighted average, total weight and weighted sum.

  4. 4

    Check each row's percentage share of the total weight.

  5. 5

    Copy the result when you are done.

About the Weighted Average Calculator

The ByteTools Weighted Average Calculator computes the weighted mean of any set of numbers: multiply each value by its weight, add them up and divide by the total weight — Σ(value × weight) / Σ(weight). Add as many value/weight rows as you need and the result updates instantly.

Weighted averages appear everywhere: course grades where exams count more than homework, portfolio returns weighted by position size, average purchase price weighted by quantity, and survey ratings weighted by group size. The tool also shows each row's normalised weight as a percentage, so you can see exactly how much influence every entry has on the final answer.

It runs 100% locally in your browser — no numbers are uploaded or stored. Weights do not need to add up to 100; the calculator normalises them for you.

Frequently asked questions

How do you calculate a weighted average?

Multiply each value by its weight, sum those products, then divide by the sum of the weights. For grades of 80, 90 and 70 weighted 20%, 30% and 50%, the weighted average is (80×20 + 90×30 + 70×50) / 100 = 78.

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

No. Because the formula divides by the total weight, any positive weights work — credit hours, share counts, sample sizes. The calculator also displays each weight as a percentage of the total so you can see the effective weighting.

When should I use a weighted average instead of a normal average?

Use a weighted average whenever the items are not equally important: grade components with different weights, prices bought in different quantities, or averages combined from groups of different sizes. A plain mean would treat every entry the same and distort the result.

What is the difference between weighted average and GPA?

A GPA is a specific weighted average where the values are grade points and the weights are course credits. You can compute a GPA with this tool by entering each course's grade points as the value and its credit hours as the weight.

Can weights be zero?

A zero weight simply removes that value from the average, which is sometimes useful for excluding an entry without deleting the row. The total weight must be greater than zero, otherwise the average is undefined and the tool will tell you.

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