How this weighted average calculator works
A weighted average is an average in which each value carries its own importance, called a weight. Rather than treating every number equally, you give each value a weight and let the larger weights pull the result toward their values. This is exactly how course grades by credit hours, assessment marks by percentage, and price averages by quantity are worked out.
The formula is: weighted average = Σ(value × weight) ÷ Σ(weights). For each pair you multiply the value by its weight to get a product, add all the products together, and divide by the sum of the weights. This calculator does that automatically and also shows the simple unweighted average — the plain mean of your values — so you can compare the two.
| Value | Weight | Value × weight |
|---|---|---|
| 90 | 2 | 180 |
| 80 | 1 | 80 |
| 70 | 1 | 70 |
| Total | 4 | 330 |
Reference note: weights do not have to sum to 1 or 100 — the formula divides by their total, so only the relative sizes matter. If every weight is equal, the weighted average equals the simple average. A total weight of zero is undefined, so the calculator asks for at least one positive weight.
Frequently asked questions
- What is a weighted average?
- A weighted average is an average in which some values count more than others. Each value is multiplied by a weight that reflects its importance, and values with larger weights pull the average more strongly toward themselves.
- How is a weighted average calculated?
- Multiply each value by its weight, add all of those products together, then divide by the sum of the weights. As a formula, weighted average = Σ(value × weight) ÷ Σ(weights).
- How is a weighted average different from a regular average?
- A regular (simple) average adds up all the values and divides by how many there are, so every value counts equally. A weighted average lets each value carry a different weight. When every weight is the same, the two are equal.
- What are weights?
- Weights are numbers that say how much each value should count — credit hours, percentages, quantities or any measure of importance. They need not add up to 100 or 1, since the calculator divides by their total, so only relative sizes matter.
- How do I weight grades or percentages?
- Use each grade or percentage as the value and the portion it is worth as the weight. If a final is worth 50 percent and two midterms 25 percent each, enter each score as a value with 50, 25 and 25 as the weights.
- When should I use a weighted average?
- Use one whenever the items are not equally important or not the same size — grades by credit hours, returns by amount invested, marks by assessment weighting, or prices by quantity. If everything counts the same, a simple average is enough.