Weighted Average Calculator
Average a list of values where each carries a different weight — grades with credit points, prices with quantities, survey scores with sample sizes.
Multiply each value by its weight, add the products, and divide by the sum of the weights.
How the weighted average calculator works
Multiply each value by its weight, add the products, and divide by the sum of the weights. If every weight is equal the result is the ordinary mean. Enter the values and weights as two comma-separated lists of the same length.
Formula: weighted mean = Σ(value × weight) / Σ(weight)
Worked examples
| Inputs | Weighted average | Note |
|---|---|---|
| 85, 72, 90, 64 weighted 4, 2, 3, 1 | 81.8 | a GPA-style weighting |
| Equal weights | 20 | equals the simple mean, 20 |
FAQFrequently asked questions
When should I use a weighted average?
Whenever some values matter more than others: subjects with more credit points, purchases with larger quantities, groups with more respondents.
Do the weights have to add up to 1 or 100?
No. The formula divides by the sum of the weights, so any positive scale works.
Can a weight be zero?
Yes — that value is ignored. Negative weights are allowed mathematically but rarely meaningful.
Is a GPA a weighted average?
Usually yes: each grade is weighted by the credit points of its unit.
What if my lists are different lengths?
The calculator asks you to fix them; each value needs exactly one weight.
Where these figures come from
- NIST Digital Library of Mathematical Functions — reference definitions for elementary and special functions
- Wolfram MathWorld — definitions and formulas for every topic on this page
- NIST/SEMATECH e-Handbook of Statistical Methods — the statistical formulas (mean, variance, z, confidence intervals, sample size)
- Common Core State Standards — Mathematics — the terms and methods taught in US schools
Last checked: September 2026. Formulas are fixed by mathematics and do not change with tax years or regulations.