Weighted Average Formula Explained, With Examples
Every weighted average result comes from one formula. Once you understand what goes into it, you can sanity-check any figure you are given, whether by an employer, a bank, a teacher or another website.
The formula
Weighted mean = Σ(value × weight) ÷ Σweight.
What each input means
- Values: the value you enter in the calculator.
- Weights: the value you enter in the calculator.
Example
For example, with these inputs:
- Values: 80, 72, 90
- Weights: 30, 30, 40
the calculator returns:
- Weighted average: 81.6
Why it matters
These calculations come up in school, at work and in daily life, from PSLE and O-Level practice to measuring a room for new flooring. Doing them by hand builds understanding, and a calculator lets you check the answer instantly.
Each formula has assumptions built in. Area formulas assume flat shapes, volume formulas assume regular solids and statistical measures assume the data you enter is the data you want to describe. Knowing the assumptions helps you pick the right tool.
In everyday life the same maths shows up in discounts, recipe scaling, renovation measurements and comparing prices per unit. Being comfortable with it saves money and avoids costly measuring mistakes.
These calculations appear throughout the Singapore syllabus, from primary school percentages and fractions to secondary school algebra and geometry. Understanding the formula makes problem sums easier because you can recognise which quantity is missing.
Related calculations
- Area of a Trapezium Calculator: Calculates the area of a trapezium from the measurements you enter.
- Area of a Parallelogram Calculator: Calculates the area of a parallelogram from the measurements you enter.
- Area of an Ellipse Calculator: Calculates the area of an ellipse from the measurements you enter.
- Area of a Rhombus Calculator: Calculates the area of a rhombus from the measurements you enter.
Use the Weighted Average Calculator to plug in your own numbers.
Run your own numbers: Weighted Average Calculator