About this calculator
Not every number counts equally. A final exam worth 50% of your grade matters more than a quiz worth 10%. The weighted average gives each value the influence it deserves.
Type the values in the first box and their weights in the second, in the same order. Weights can be percentages, credits or any positive numbers: only the ratio between them matters.
Worked examples
Real numbers, worked out by the same calculator. Press “Use these numbers” to try one above.
Coursework 80, test 70, exam 90 (30/20/50)
- Weighted average
- 83
- Total weight
- 100
- Simple average (no weights)
- 80
The weighted average of 3 values is 83 (a simple average would give 80).
Show the working
- Multiply each value by its weight and add them up: 80 × 30 + 70 × 20 + 90 × 50 = 8,300.
- Add up the weights: 100.
- Weighted average = 8,300 ÷ 100 = 83.
Equal weights give the simple average
- Weighted average
- 6
- Total weight
- 3
- Simple average (no weights)
- 6
The weighted average of 3 values is 6 (a simple average would give 6).
Show the working
- Multiply each value by its weight and add them up: 4 × 1 + 8 × 1 + 6 × 1 = 18.
- Add up the weights: 3.
- Weighted average = 18 ÷ 3 = 6.
Average price: 10 units at £3, 30 at £4
- Weighted average
- 3.75
- Total weight
- 40
- Simple average (no weights)
- 3.5
The weighted average of 2 values is 3.75 (a simple average would give 3.5).
Show the working
- Multiply each value by its weight and add them up: 3 × 10 + 4 × 30 = 150.
- Add up the weights: 40.
- Weighted average = 150 ÷ 40 = 3.75.
The formula
Weighted average = (v₁w₁ + v₂w₂ + …) ÷ (w₁ + w₂ + …). Multiply each value by its weight, add the results and divide by the total weight.
Common uses
- Course and module grades
- Average purchase price when you bought at different prices
- Portfolio returns weighted by amount invested
- Survey results combining groups of different sizes
Do weights have to add up to 100?
No. 30, 20 and 50 give the same answer as 3, 2 and 5. The calculator divides by the total weight, so any positive numbers work. If your weights are percentages, they typically total 100.
Frequently asked questions
What is a weighted average?
An average where some values count more than others, according to a weight you assign.
How do I calculate a weighted grade?
Multiply each score by its percentage weight, add the results, and divide by the total weight (100 if the weights are percentages).
What if the weights don't add to 100?
That's fine. The calculator divides by whatever they add up to.
How is it different from the normal average?
A normal average gives every value the same weight. The calculator shows both so you can see the effect.
Can a weight be zero?
Yes: that value is ignored. Negative weights are not allowed.
Formulas tested against hand-worked answers. Last reviewed 29 September 2026. These calculators do arithmetic only; they are not financial, tax or legal advice.