Education
Weighted Average Calculator
Find a weighted mean from paired values and weights.
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Transparent methodology
What the result includes—and what it does not
Built for anyone averaging numbers that carry unequal importance — course grades, survey scores, portfolio positions, blended rates — where a plain average would give the wrong answer.
Calculation method
- 1"Weighted average" and "weighted mean" are two names for the same calculation, so a single formula and a single page cover both terms.
- 2Both boxes are read as lists of numbers separated by commas, spaces, semicolons, or line breaks, and the lists are paired by position: the first weight belongs to the first value.
- 3Weighted average = (value₁ × weight₁ + value₂ × weight₂ + …) ÷ (weight₁ + weight₂ + …).
- 4The total weight — the denominator of that division — is returned as a second result so the divisor is visible rather than assumed.
Assumptions and limits
- Weights do not need to sum to 1 or to 100. The calculation divides by whatever the weights actually total, so 20/50/30 and 0.2/0.5/0.3 return the same weighted average.
- Values and weights are matched by position and both lists must hold the same count of numbers; unequal lists return an error instead of a result, and a missing entry shifts every pair after it.
- Only bare numbers are read. Anything that is not a number — a label, a unit, a currency symbol — is dropped entirely, which shifts every pair after it, while a leading, trailing or doubled separator is read as an extra zero.
- If the weights total zero the result is undefined and shown as a dash. Displayed results are rounded — the weighted average to six decimal places, the total weight to four — while the arithmetic behind them is unrounded.
Worked example
Three scores weighted 20, 50, and 30
Input: Values 80, 92, 75 with weights 20, 50, 30.
Output: Weighted average: 84.5. Total weight: 100.
Primary sources
- Eurostat Statistics Explained — Glossary: Weighted averageOfficial EU statistical glossary. It defines the concept as "a weighted average or weighted mean", which is why both terms are answered on one page here.
- Wolfram MathWorld — Weighted MeanStandard mathematics reference for the definition. It states the formula with weights normalized to sum to 1, which is equivalent to dividing by the total weight as this tool does.
How to use it
Three steps. One clear answer.
- 1Enter or paste the values requested by the tool.
- 2Review the input units and choose any relevant options.
- 3Calculate, then copy or download the result you need.
Built for trust
Useful without the friction.
- No registration or paywall before your result.
- Responsive controls for phone, tablet, and desktop.
- Clear assumptions and warnings where estimates have limits.
Frequently asked questions
Is a weighted mean the same as a weighted average?
Yes. They are two names for the same calculation, and this page covers both — there is no separate weighted mean calculator to look for. Eurostat's statistical glossary defines the term as "a weighted average or weighted mean".
How do you calculate a weighted average?
Multiply each value by its own weight, add those products together, then divide by the sum of the weights. With values 80, 92, 75 and weights 20, 50, 30 that is 8,450 ÷ 100 = 84.5.
What is the difference between a weighted average and a normal average?
A plain arithmetic mean gives every value equal influence; a weighted average lets some values count for more. The two agree exactly when all weights are equal — the plain mean of 80, 92, 75 is 82.333333, but weighting them 20, 50, 30 gives 84.5.
Do the weights have to add up to 100?
No. The calculation divides by whatever your weights total, so percentages, credit hours, unit counts, or decimals all work as long as you use one consistent scale. The total weight is shown as a second result so you can check the divisor.
How do I work out a weighted grade average?
Enter each score in the values box and the percentage or credit weight of the matching assessment in the weights box, in the same order. If your weights cover only part of the course, the result is the average of that part, not the final grade.
Why does it say each value needs one matching weight?
The two boxes contain a different count of numbers. Any entry that is not a bare number is dropped, and a stray comma or space at the start or end of a box is read as an extra zero — either one changes the count.
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