Grade Calculator
List each graded piece of work with its score and its weight — the share of the course grade it counts for. The calculator multiplies each score by its weight, adds them up and divides by the total weight to give your weighted average.
Answer
Weighted grade
84.3%
Across 3 items worth 100% of the course.
- of the course counted
- 100%
- plain average, for comparison
- 85
Check the work
Every line comes from the same calculation as the answer.
grade = Σ (score × weight) ÷ Σ weight
| Σ score × weight | 92 × 20 + 78 × 30 + 85 × 50 | 8,430 |
|---|---|---|
| Σ weight | 20 + 30 + 50 | 100 |
| grade | 8,430 ÷ 100 | 84.3 |
How it works
Most courses do not average scores equally. A final exam worth half the grade counts far more than homework worth a fifth. A weighted average multiplies each score by its weight before adding, so heavier items pull the result towards their score.
With homework at 92 counting 20%, a midterm at 78 counting 30% and a final at 85 counting 50%, the weighted average is (92 × 20 + 78 × 30 + 85 × 50) ÷ 100 = 84.3. A plain average of the three scores would say 85, which overstates the effect of the strong homework mark.
Weights do not have to add up to 100. Part-way through a term, the work marked so far might cover only half the course; dividing by the weights entered gives your average on that work alone, which is how most grade portals report a current grade.
Formula
grade = (score₁ × weight₁ + score₂ × weight₂ + …) ÷ (weight₁ + weight₂ + …)
Each score is multiplied by its weight, the products are added, and the sum is divided by the total of the weights.
Worked examples
- Try these numbers
Homework, midterm and final
- 92 × 20 = 1,840; 78 × 30 = 2,340; 85 × 50 = 4,250.
- The products add up to 8,430 and the weights to 100.
- 8,430 ÷ 100 = 84.3.
The weighted grade is 84.3.
- Try these numbers
Halfway through the term
- 90 × 25 + 70 × 25 = 4,000.
- Only 50% of the course has been marked, so divide by 50.
- 4,000 ÷ 50 = 80.
The current grade on marked work is 80.
- Try these numbers
Equal weights
- With equal weights each score counts once: 60 + 80 + 100 = 240.
- 240 ÷ 3 = 80.
Equal weights give the plain average, 80.
Inputs and results
- Item
- An assignment, quiz, exam or category, for your own reference.
- Score
- The mark for that item, on the same scale as the others, usually a percentage.
- Weight
- How much the item counts towards the course, usually a percentage of the grade.
- Weighted average
- Sum of score × weight divided by the sum of weights.
- Weight counted
- The total of the weights entered; 100 when the whole course is included.
When to use it
- Checking a current course grade from the marks returned so far.
- Seeing how much a single assignment moved the overall grade.
- Comparing a weighted average with the plain average of the same scores.
Common mistakes
- Entering points instead of percentages for a score, such as 18 for 18 out of 20; convert it to 90 first.
- Typing weights as decimals in some rows and percentages in others; use one form throughout.
- Leaving out an item that has been marked, which shifts the average towards the remaining work.
What it does not do
- It does not apply a school’s rounding, curve, drop-the-lowest rule or letter-grade boundaries.
- It assumes every score is on the same scale, such as percentages out of 100.
- It does not predict a final result; use the final grade calculator to find the score you need.
Method and assumptions
The weighted average is the sum of each score multiplied by its weight, divided by the sum of the weights. Weights are used in proportion to each other, so 20/30/50 and 0.2/0.3/0.5 give the same result.
No rounding is applied to the result; the displayed figure is shortened to two decimal places and the exact value appears in the working.
Assumptions
- All scores use one scale.
- Weights are proportional; they need not total 100.
Edge cases
- A row needs both a score and a weight; a row with only one is flagged.
- Weights must not be negative, and at least one must be greater than zero.
- Scores above 100, such as extra credit, are allowed and counted as entered.
Sources and corrections
This calculator uses an elementary formula, so it needs no outside data source. The method, the rounding rules and how a reported error is corrected are set out in the site standards.
Result looks wrong?
Send the inputs you used and the answer you expected. Every report is checked against the formula and its tests, and confirmed errors are corrected in public.