Weighted Average Calculator
Enter each value with its weight. Weights can be percentages or credits, but use the same kind in every row.
%
Use the same units as the weights above.
#
Weighted average:
Sum of weights:
Sum of value × weight:
Calculation:
This calculator finds your weighted average from values and weights, and it also tells you what grade you need on the final exam to reach the average you want. Weights can be percentages (30%, 40%) or credits (4, 3, 1).
Below you will find the formulas, solved examples and a table of the final exam grade you need for different targets.
How to use the weighted average calculator?
Step 1: Pick Weighted average to get the average of your grades, or Grade needed on the final to find out what you must score on the exam you still have to take.
Step 2: In each row, enter the value (the grade) and its weight. Add row gives you up to 20 rows and the × button removes one. Decimals can use a point or a comma.
Step 3: If you picked the grade needed on the final, also enter the weight of the final (in the same units as the other weights) and the average you want. Grades are on a 0 to 100 scale.
Step 4: Press Calculate or the Enter key. The Calculation box shows every operation with your numbers.
Weighted average formula
A weighted average multiplies each value by its weight, adds the products and divides by the sum of the weights:
| average = (v1 × w1 + v2 × w2 + ... + vn × wn) ÷ (w1 + w2 + ... + wn) |
The weights do not have to add up to 100. You always divide by the sum of the weights you enter, so percentages, credits or hours all work the same way.
Formula for the grade needed on the final
Say your grades so far carry a total weight W, the final carries f and you want an average T. The grade x you need satisfies (sum of v × w + x × f) ÷ (W + f) = T. Solving for x gives:
| x = (T × (W + f) - sum of v × w) ÷ f |
If x comes out higher than the top of the scale (100), you cannot reach that average with the final. If x is at or below the bottom of the scale, you already have it secured.
Weighted average examples
Example 1: Average with percentage weights
You have two exams worth 30% each and homework worth 40%. Your grades are 85, 92 and 78.
85 × 30 + 92 × 30 + 78 × 40 = 2550 + 2760 + 3120 = 8430
Sum of weights: 30 + 30 + 40 = 100
8430 ÷ 100 = 84.3
The weighted average is 84.3.
Example 2: Average with credits
Four courses with grades of 90, 78, 85, 100 and credits of 4, 3, 3, 1. Here the weight of each course is its credits.
90 × 4 + 78 × 3 + 85 × 3 + 100 × 1 = 360 + 234 + 255 + 100 = 949
Sum of credits: 4 + 3 + 3 + 1 = 11
949 ÷ 11 ≈ 86.2727
The weighted average is about 86.2727.
Example 3: Grade needed on the final
You scored 78 and 82 on two exams worth 35% each. The final is worth 30% and you want an average of 80. The weights add up to 35 + 35 + 30 = 100.
Sum of value × weight: 78 × 35 + 82 × 35 = 2730 + 2870 = 5600
x = (80 × 100 - 5600) ÷ 30 = 2400 ÷ 30 = 80
You need 80 on the final.
Example 4: When the average is out of reach
You have 55 on the part worth 85%, the final is worth 15% and you want 70. The scale runs from 0 to 100.
x = (70 × 100 - 4675) ÷ 15 = 2325 ÷ 15 = 155
The grade needed, 155, is above the top of the scale (100). Even with 100 on the final your average would be 61.75. The calculator warns you and shows that highest possible average.
Grade you need on the final
With a 78 average on the part worth 70% and a final worth 30% (scale of 0 to 100), this is what you need to score depending on your target average:
| Target average | Grade needed on the final | Result |
|---|---|---|
| 50 | - | Already secured |
| 70 | 51.3333 | Reachable |
| 75 | 68 | Reachable |
| 80 | 84.6667 | Reachable |
| 85 | 101.3333 | Out of reach |
| 95 | 134.6667 | Out of reach |
Frequently asked questions
What is the difference between a simple and a weighted average?
In a simple average every grade counts the same. In a weighted average each grade counts differently. With grades of 80 and 100, the simple average is 90. If the second one is worth 70% and the first 30%, the weighted average is 94.
Do the weights have to add up to 100?
No. The result is always divided by the sum of the weights. For example, weights of 2 and 3 give 92, the same as 40 and 60, which give 92.
How do I calculate an average by credits?
Use the credits of each course as its weight, as in example 2. A 4-credit course then moves the average more than a 1-credit course.
What if the grade I need is higher than the maximum?
It means that, with your current grades, that average can no longer be reached with the final. You can lower the target average, or check with your instructor whether other graded work still counts.
Learn more
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