Weighted Average Calculator
Some numbers matter more than others. A weighted average gives bigger numbers more say in the final result, instead of treating everything equally. Enter your values and weights below to see it in action.
What a weighted average actually does
A plain average treats every number the same. Five test scores get added up and divided by five, no matter how much each test counted. A weighted average fixes that. It lets you say some numbers count more, based on a weight you choose. A big exam pulls your grade more than a small quiz. A large investment moves your portfolio return more than a small one.
Σ means “add all of these up.” Value is each individual number you’re averaging. Weight is how much that number should count, relative to the others. You multiply each value by its own weight, add all of those together, then divide by the total of all the weights.
Why the plain average can be misleading
Two students can have the exact same three scores and still end up with different final grades, simply because their assignments were weighted differently. This is exactly why weighted averages matter. They reflect what actually counts, not just what was measured.
Where you’ll actually use this
Grades and GPA
Courses with more credit hours count more toward your overall GPA than a one credit elective.
Portfolio returns
A stock that makes up 60% of your portfolio should influence your total return far more than one that’s only 5%.
Inventory costing
Businesses often use weighted average cost to value stock bought at different prices over time.
Survey and review scores
A review from a thousand customers usually deserves more weight than a review from three people.
Frequently asked questions
Then the weighted average and the plain average will be exactly the same. Weighting only changes the result when the weights actually differ from each other.
No. The formula divides by the total of your weights automatically, so they can be percentages, hours, dollars, or any unit at all.
Yes. A weight of zero simply removes that value from the result entirely, as if it were never included.
No. Weighted average blends several numbers into one fair result. CAGR and ROI measure growth over time instead. They solve different problems.
Applying this to an investment portfolio?
See how a return like this compounds over time.
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