Weighted Average Calculator
Find the weighted average of any set of values where each item carries a different importance. Choose a mode for grades, GPA or general math, enter values and their weights or credit hours, and get the weighted mean alongside a full per-item breakdown and a reverse-solve for a target score.
Formula
Worked example
Values 85, 90, 78 with weights 0.2, 0.3, 0.5: (85x0.2 + 90x0.3 + 78x0.5) / (0.2 + 0.3 + 0.5) = (17 + 27 + 39) / 1 = 83.
How a weighted average works
A weighted average gives each value an importance factor, called its weight, instead of treating every value equally. You multiply each value by its weight, add up those products, and divide by the total of all the weights. When every weight is the same, the result collapses back to an ordinary arithmetic mean. Weights let bigger or more reliable items pull the average toward them, which is exactly what a plain average cannot do. The formula is: weighted mean = sum(value times weight) divided by sum(weights).
Grade and GPA mode: how the modes differ
In Grade mode, your scores are percentages (0-100) and your weights are the percentage each component is worth in the final grade. Weights do not need to sum to 100; if you enter only the components you have completed so far, the calculator weights them relative to each other and the reverse-solve feature tells you what score you need on the remaining component to hit your target. In GPA mode, enter letter grades (A+, A, A-, B+, ..., F) and the credit hours for each course. The calculator converts each letter grade to the 4.0-scale grade point using the standard US conversion table and weights each course by its credit hours to produce a credit-weighted GPA, exactly as a registrar office would.
Reverse-solve: what score do I need?
Turn on the reverse-solve toggle in Grade mode to answer "what do I need on my final exam?" Supply the weight of the remaining component (for example, 25 for a final worth 25%) and your target course average. The calculator solves the formula backwards: needed score = (target times total weight including remaining, minus current weighted sum) divided by the remaining weight. If the result exceeds 100 or falls below 0, your target is outside the possible range given your current grades.
The per-item breakdown table
The schedule table below the result shows each item, its value, its raw weight, its weight as a share of the total, the product of value times weight, and the percentage contribution of that product to the weighted sum. The contribution column answers the practical question: which item is pulling my average up or down the most? An item with a large weight and a high score contributes a large positive percentage; an item with a large weight and a low score drags the average down the most.
Where weighted averages are used
Weighted averages appear in nearly every field where some numbers should count more than others. Schools weight exams more heavily than homework to reflect mastery over practice. Investors compute a portfolio return by weighting each holding by its dollar value so a large position matters more than a small one. Survey researchers weight responses to correct for over- or under-represented groups and produce estimates that match the true population. Businesses use the weighted average cost of capital (WACC) to combine the cost of equity and debt by their proportions in the capital structure. In every case the weights encode how much each value should influence the final figure.
Values and weights must line up
The single most common mistake is mismatched lists: five values but only four weights, or weights entered in the wrong order. Each value needs exactly one weight, and the order matters because the first weight is paired with the first value. Weights do not have to add up to 1 or 100; the formula divides by their total, so 2, 3, 5 and 0.2, 0.3, 0.5 produce the identical weighted average. Percentages that sum to 100 are common because they are easy to read, but they are not required.
Letter grade to GPA conversion (US 4.0 scale)
| Letter grade | GPA points | Typical percentage range |
|---|---|---|
| A+ | 4.0 | 97-100% |
| A | 4.0 | 93-96% |
| A- | 3.7 | 90-92% |
| B+ | 3.3 | 87-89% |
| B | 3.0 | 83-86% |
| B- | 2.7 | 80-82% |
| C+ | 2.3 | 77-79% |
| C | 2.0 | 73-76% |
| C- | 1.7 | 70-72% |
| D+ | 1.3 | 67-69% |
| D | 1.0 | 60-66% |
| F | 0.0 | Below 60% |
Standard conversion used by most US colleges and universities. Some institutions cap A+ at 4.0 rather than 4.3.
Frequently asked questions
Do the weights need to add up to 1 or 100?
No. The formula divides by the sum of the weights, so any consistent scale works. Weights of 2, 3, 5 give the same result as 0.2, 0.3, 0.5 or 20, 30, 50. Percentages that sum to 100 are common because they are easy to read, but they are not required. The calculator shows the total weight so you can verify your inputs.
What is the difference between a weighted and a simple average?
A simple average treats every value equally: add them up and divide by the count. A weighted average lets some values count for more by assigning each one a weight before summing. If all the weights are equal, the two answers are identical. When weights differ, the weighted mean shifts toward the values with the largest weights.
How do I calculate my GPA with this calculator?
Switch to GPA mode. Enter your letter grades as a comma-separated list (for example A, B+, A-, C) and your credit hours in the same order (for example 4, 3, 3, 2). The calculator converts each letter grade to its GPA point value on the standard 4.0 scale and weights each course by its credit hours, exactly as a registrar would compute your cumulative GPA.
What score do I need on my final exam to get an A?
Switch to Grade mode, enter your scores so far with their weights, then turn on the reverse-solve toggle. Enter the weight of your remaining exam (for example 30 for a final worth 30%) and your target average (for example 90 for an A). The calculator solves for the score you need. If the result exceeds 100, your target is no longer achievable with the remaining component.
Why do I need the same number of values and weights?
Each value is paired with exactly one weight, in order. If the two lists have different lengths, there is no way to know which weight belongs to which value, so the calculation cannot proceed. Check that you have a matching comma for every entry in both fields.
Can I use this calculator for a portfolio return?
Yes. In General mode, enter each asset return as a value (for example 12.5 for 12.5%) and the dollar value of that holding as its weight. The weighted average gives you the portfolio return weighted by position size, which is the standard way to compute portfolio performance.