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Weighted Average Calculator

Enter values and weights to get your weighted mean instantly

Free · Instant
Label (optional)
Value
Weight

How the Weighted Average Formula Works

A weighted average assigns each data point a weight that reflects how much it should count toward the final result. The formula is straightforward:

Weighted Average = Σ(value × weight) / Σ(weights)
Where Σ means "sum of all items"

This contrasts with a simple average, which divides the sum of values by the count. When weights differ, the weighted average moves toward items with higher weights. If all weights are equal, the result is identical to a regular mean.

Example with three grade components:
Quiz (85) × weight 20 = 1,700
Midterm (78) × weight 30 = 2,340
Final (92) × weight 50 = 4,600
Sum of products = 8,640
Sum of weights = 100
Weighted Average = 8,640 / 100 = 86.40

Who Uses a Weighted Average Calculator?

🎓
Students
Calculate final course grades when each component (quizzes, exams, projects) carries a different percentage.
📊
Teachers & Professors
Verify grade calculations quickly and communicate how each assessment affects the final score.
💹
Investors & Analysts
Compute weighted average cost basis, portfolio returns, or index compositions by market cap.
📋
Project Managers
Score vendor bids, risk factors, or evaluation criteria where some dimensions matter more than others.

You may also need this calculator when:

  • Computing a GPA across courses with different credit hours
  • Averaging survey responses where question importance differs
  • Calculating weighted return on a multi-asset portfolio
  • Scoring job candidates across multiple criteria
  • Determining an aggregate rating from reviews of different sample sizes

How to Use This Calculator

1
Enter your items
Start with the default three rows or clear them. Type an optional label (e.g., "Final Exam") so you can identify each row in the results.
2
Enter the value for each item
Type the score, return, rating, or any numeric value in the Value column. Values can be any real number, including decimals.
3
Enter the weight for each item
Type the weight in the Weight column. Weights can be percentages (20, 30, 50), raw numbers (2, 3, 5), or any positive value. They do not need to sum to 100.
4
Add or remove rows as needed
Click "+ Add Row" to add more data points. Click the × button to remove a row (minimum two rows required).
5
Click Calculate
Hit the Calculate button to compute the weighted average. Results show the overall mean, a breakdown table with each item's contribution, and a weight distribution bar chart.
6
Interpret your results
The large number at the top is your weighted average. The table shows how each item's value and weight combine. Higher-weight items shift the average toward their value.

Worked Example

Emily is finishing her semester and wants to know her final grade before the official report. Her professor uses the following grade breakdown: quizzes 20%, midterm 30%, final exam 50%.

Emily's scores:
Quiz Average: 85 × weight 20 = 1,700
Midterm Exam: 78 × weight 30 = 2,340
Final Exam: 92 × weight 50 = 4,600
Sum of products: 8,640
Sum of weights: 100
Final Grade = 8,640 / 100 = 86.40 (B+)
What Does the Result Mean?

Emily's quiz score of 85 is decent, but because quizzes are only 20% of the grade, they contribute just 17 points to the weighted average. Her midterm at 78 is the weakest component but still contributes 23.4 points. Her final exam performance of 92, worth half the grade, pulls the average up significantly, contributing 46 points. The result of 86.40 is higher than the simple average of (85+78+92)/3 = 85, reflecting that the high final exam score carries more weight.

Common Mistakes to Avoid

!
Using a simple average when weights differ
Adding all scores and dividing by the count ignores how much each component is worth. If your final exam is 50% of your grade, it deserves 5× the influence of a 10% quiz.
!
Entering weights that sum to more than 100 accidentally
If your course syllabus lists weights summing to 100%, double-check you have not duplicated a row. The calculator normalizes any weights, but you may not realize a data entry error changed your result.
!
Confusing value and weight columns
A common mix-up is entering the weight percentage in the value column and the score in the weight column. Always label rows to catch this before clicking Calculate.
!
Comparing weighted averages with different weight structures
A weighted GPA from one school may not be comparable to another if the credit hour structures differ. Always clarify what weights were used before comparing results across systems.

Frequently Asked Questions

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Sources

1
NIST/SEMATECH e-Handbook of Statistical Methods
Definition and properties of the weighted mean, engineering statistics reference.
2
Khan Academy: Weighted Averages
Educational explanation of weighted averages with grade and GPA examples.
3
CFA Institute Curriculum: Portfolio Mathematics
Use of weighted averages for portfolio return and cost-basis calculations in finance.
📐
Dr. Rachel Kim, Ph.D.
Applied Mathematics Educator, University of Michigan

Dr. Kim teaches undergraduate statistics and has used weighted averages in academic grading, survey analysis, and data science curricula for over 12 years. She developed this tool to help students grasp how grade weighting affects their final score before official results are posted.

Published April 2025 · Updated April 2025
Formula Reference
WA = Σ(vᵢ × wᵢ) / Σ(wᵢ)
vᵢ = value of item i
wᵢ = weight of item i
Weights do not need to sum to any specific number. The formula normalizes automatically.
Quick Examples
Grading
Quiz 85 (20%), Midterm 78 (30%), Final 92 (50%) → 86.40
GPA
3-credit A (4.0) + 4-credit B (3.0) → GPA 3.43
Portfolio
Stock A 8% return (60%) + Bond B 3% return (40%) → 6.0% return
Pro Tip

If your weights are in percentages that should add to 100%, always verify their sum before calculating. A common syllabus error is listing components that total 95% or 105%. This calculator handles it, but your professor may grade differently.

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