Weighted Average Calculator

A weighted average is one of the most fundamental statistical calculations in academia, finance, and data science. Unlike a simple arithmetic mean where every entry carries identical mathematical importance, a weighted average assigns varying degrees of significance—or "weight"—to individual data points.

In university coursework, professors rarely grade every assignment equally. A 10-minute weekly pop quiz should not hold the same power over your semester grade as a 3-hour comprehensive final examination. Course rubrics reflect this by assigning percentages: for instance, homework at 20%, midterm exams at 30%, laboratory work at 15%, and the final exam at 35%.

To compute a weighted grade, you multiply each score by its corresponding weight, add all the products together, and divide by the total sum of the weights: Weighted Average = Σ(Value × Weight) / Σ(Weights). Consider a student who scores 85 on homework (wt 20), 80 on midterms (wt 30), 92 on labs (wt 15), and 88 on the final (wt 35). The products are 1,700, 2,400, 1,380, and 3,080, totaling 8,560. Dividing by the 100% total weight yields a final grade of 85.60%.

Notice that if you simply averaged the four raw scores—(85 + 80 + 92 + 88) / 4—you would get 86.25%. The simple average overstates the student’s grade because it treats the high 92 score on a 15% lab with the same importance as the 80 score on a 30% exam. This critical distinction is why understanding weighted means is essential for academic success.

Practical Guidance: When working in percentage mode, always check that your weight allocations sum to exactly 100%. If your weights add up to 90% or 110%, our calculator displays a friendly warning banner to help you identify missing syllabus components. For teachers and investors, the "Points" mode allows easy calculation using raw points, credit hours, or asset values.