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Weighted Average Calculator

Find the weighted mean of up to three values.

How it is calculated

A weighted average gives each value an importance, so items with bigger weights pull the result harder: average = (v₁w₁ + v₂w₂ + v₃w₃) ÷ (w₁ + w₂ + w₃). Here v is the value (a grade, price, score) and w is its weight (credits, quantity, percentage). The tool takes up to three value/weight pairs. A pair is skipped if either box is empty, so you can use only two pairs. The weights do not need to add up to 100; the division by the weight total takes care of scaling. If the total weight is zero there is no result. Rounded to two decimals.

Worked example

An exam is 30% of a course, homework 20% and a project 50%, with scores 80, 65 and 90. Multiply each score by its weight: 80 × 30 = 2,400; 65 × 20 = 1,300; 90 × 50 = 4,500. The sum is 8,200. Total weight is 30 + 20 + 50 = 100. Average: 8,200 ÷ 100 = 82.00. The plain average of the three scores would be 78.33, but the heavily weighted project lifts the weighted result.

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Common mistakes

  • Averaging the values plainly when the items count differently, such as courses with different credits.
  • Entering a value without its weight. The pair is ignored silently, so the result is based on fewer items than you think.
  • Putting the weights as percentages that do not add to 100 and assuming the result is wrong. It is still correct, because the division rescales.
  • Swapping value and weight columns, which gives a nonsensical average.

About this calculator

A weighted average multiplies each value by its own weight, sums those products, and divides by the total of the weights — Σ(value × weight) ÷ Σ(weight) — instead of treating every number as equally important the way a plain average does. This calculator handles up to three value/weight pairs at once.

It's the method behind a course grade where exams count more than homework, a portfolio's blended return when positions are different sizes, or an inventory's average cost when purchase batches arrived at different prices and quantities. Students checking a final grade, analysts blending returns, and shop owners costing stock all rely on this instead of a simple mean because ignoring the weights would give a misleading answer.

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Comments (1)

  • Editorial team

    The tool can also answer a what-if question about a final exam. Put your known scores with their weights in the first two pairs, then try values for the last pair until the result reaches your goal. With 80 at weight 30 and 65 at weight 20, a final worth 50 needs 76 to land on 75 overall. Which target grade are you working toward?

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