Weighted Average Calculator
Calculate weighted means for grades, portfolios, or custom data
Calculate weighted average: Σ(value × weight) / Σ(weight)
What Is a Weighted Average?
A weighted average (weighted mean) is an average where some values count more than others. Instead of adding values and dividing by the count, you multiply each value by its weight, add those products, and divide by the total weight:
Weighted average = Σ(value × weight) ÷ Σ(weights)
A simple average treats every data point equally — which is just a weighted average where all weights are 1. The weighted version matters whenever importance differs: exam grades with different credit hours, portfolio holdings of different sizes, or survey results from groups of different sizes.
Worked Example: Course Grade
Suppose homework counts 20%, the midterm 30%, and the final 50%. You scored 92 on homework, 78 on the midterm, and 85 on the final. Your course grade is:
(92 × 0.20) + (78 × 0.30) + (85 × 0.50) = 18.4 + 23.4 + 42.5 = 84.3
A simple average of the three scores would be 85 — the weighted average is lower because the weakest score (the midterm) carried substantial weight.
GPA Mode
GPA is a weighted average where grade points are weighted by credit hours. On the standard 4.0 scale, A = 4.0, B = 3.0, C = 2.0, D = 1.0, F = 0. A student earning an A in a 4-credit course, a B in a 3-credit course, and a C in a 2-credit course has GPA = (4.0×4 + 3.0×3 + 2.0×2) / 9 = 29/9 ≈ 3.22. The GPA tab handles the grade-to-points conversion and the credit weighting for you, and reports the letter-grade equivalent.
Portfolio Mode
A portfolio's return is the weighted average of its holdings' returns, weighted by how much money is in each. If 60% of your portfolio gains 10%, 30% gains 4%, and 10% loses 5%, the overall return is 0.6×10 + 0.3×4 + 0.1×(−5) = 6.7%. The Portfolio tab also shows each holding's contribution, so you can see exactly what drove the result.
Tips for Correct Results
- Weights do not need to sum to 100 — the calculator normalizes by the total weight, so you can use percentages, credits, dollars, or counts directly.
- Keep units consistent: mixing percentage weights with dollar weights in one calculation will skew the result.
- A weighted average always falls between the smallest and largest value; if yours does not, check for a data-entry error.
Frequently Asked Questions
How do I calculate a weighted average?+
Multiply each value by its weight, add up the products, then divide by the sum of the weights. For example, scores of 80 and 90 with weights 1 and 3 give (80×1 + 90×3) / 4 = 87.5. Enter values and weights in the Basic tab and the calculator shows the full breakdown.
What is the difference between a weighted average and a simple average?+
A simple average treats every value equally; a weighted average lets some values count more. With scores of 80 and 90, the simple average is 85, but if the 90 carries three times the weight the weighted average is 87.5. Use weights whenever items differ in importance, size, or frequency.
How does the GPA calculation work?+
GPA is a weighted average of grade points using credit hours as weights: multiply each course's grade points (A = 4.0, B = 3.0, and so on) by its credits, sum, and divide by total credits. The GPA tab does this automatically from your numeric grades and credit hours and displays the resulting GPA with its letter equivalent.
Do the weights have to add up to 100%?+
No. The calculator divides by the actual sum of your weights, so any consistent weighting works — percentages, credit hours, dollar amounts, or item counts. Weights of 20/30/50 give exactly the same result as 2/3/5.
Is the weighted average calculator free and does it work on mobile?+
Yes. It is free, requires no sign-up, and runs entirely in your browser, so your grades or portfolio figures never leave your device. You can add or remove rows as needed, and the layout works on phones, tablets, and desktops.
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