Free 100% In-Browser Tool

Weighted Average Calculator: Calculate Weighted Mean

Calculate the weighted average (weighted mean) for grades, portfolios, and statistical datasets with step-by-step arithmetic.

Quick Answer:The weighted average is calculated by multiplying each value by its corresponding weight, summing the products, and dividing by the sum of all weights: ∑(x × w) / ∑w.

Initializing tool...

Privacy First: 100% Client-Side Processing

Processed in your browser. Files are never uploaded.

How to Use the Weighted Average Calculator (Grade & Investment)

1Enter your values (scores, prices, or rates) and their respective weights (percentages or counts).
2Click 'Add Value & Weight' to insert additional data rows as needed.
3Review the total weighted average, sum of products, and total weight sum.
4Inspect the mathematical formula breakdown.

Formula & How It Works

Weighted Mean Formula

x̄_w = (w₁x₁ + w₂x₂ + ... + wₙxₙ) / (w₁ + w₂ + ... + wₙ)

Each value x_i is multiplied by its weight w_i. The sum of these products is normalized by dividing by the total weight.

Worked Examples

College Semester Course Grade

Input: Homework 85 (wt 20), Midterm 90 (wt 30), Final 78 (wt 50)

Explanation: (85×20 + 90×30 + 78×50) / (20 + 30 + 50) = (1700 + 2700 + 3900) / 100 = 8300 / 100 = 83.0.

Result: Weighted Average: 83.0

Stock Portfolio Buy-In Average

Input: 10 shares at $50, 40 shares at $70

Explanation: (10×50 + 40×70) / (10 + 40) = (500 + 2800) / 50 = 3300 / 50 = $66.00.

Result: Weighted Average: $66.00 per share

Customer Review Rating

Input: Five stars: 100 reviews, Four stars: 20 reviews, One star: 10 reviews

Explanation: (5×100 + 4×20 + 1×10) / (100 + 20 + 10) = 590 / 130 = 4.538.

Result: Weighted Rating: 4.54 / 5.0

Frequently Asked Questions

What is a weighted average?▼

A weighted average is an average that multiplies each number by a weight representing its importance before dividing by the sum of all weights.

Do weights have to sum to 100?▼

No. The formula divides by the sum of all weights, so weights can be raw credits, counts, or hours.

How do you calculate GPA using weighted average?▼

Multiply each course grade point by its credit hours, sum them up, and divide by total credit hours taken.

Can weights be negative?▼

In standard practical applications (grades, investments, reviews), weights must be positive numbers.

Can I add as many rows as I need?▼

Yes, you can dynamically add unlimited value-weight pairs.

Is this calculation private?▼

Yes, all data processing occurs entirely within your browser.

Quick Reference & Conversion Table

Value (x)	Weight (w)	Product (x × w)	Normalized Weight %
85	20	1,700	20.0%
90	30	2,700	30.0%
78	50	3,900	50.0%
Total	100	8,300	100.0%

⚠️ Common Pitfalls to Avoid

•Calculating a simple arithmetic mean (adding values and dividing by count) when items have unequal weights.
•Assuming weights must add up to 100% (the formula automatically normalizes by dividing by the sum of weights).
•Swapping the values and the weights in the input columns.

💡 Practical Real-World Uses

•College professors and students calculating final weighted course grades.
•Investors calculating dollar-cost averaging and weighted cost basis for stocks and crypto.
•Product managers calculating customer satisfaction (CSAT) scores across survey cohorts.

Weighted Average vs Simple Average

✓A simple average treats every data item equally regardless of importance or quantity.
✓A weighted average scales each item's contribution by its assigned importance, frequency, or share.

Last reviewed & updated: 2026-11-01

Free & Open Access

Related Utilities

Explore complementary calculators and converters with instant client-side execution