How would I be able to calculate my overall average grade (or grade point average) for these courses?
| Course | Course Credit (weight) | Course Grade |
|---|---|---|
| Biology 101 | 45 | 86 |
| Psychology 210 | 30 | 74 |
| Chemistry 250 | 45 | 88 |
| English 200 | 60 | 77 |
My understanding is by simply adding the course grades column together and dividing by the total cumulative possible marks.
(86+74+88+77)/400 = 0.8125
But this number seems very strange in the 0 to 4 GPA.
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$\begingroup$You calculated an unweighted GPA. To weight it, you must factor in the course credit variable.
> sum=45+30+45+60
> (86*45+74*30+88*45+77*60)/sum
[1] 81.5As the original units are in a 0-100 scale, your weighted gpa is about a B-.
To convert to a 4.0 scale, simply use the appropriate unit conversion
> 81.5*4/100
[1] 3.26Your original calculation was missing a multiplication by 4. The procedure for your unweighted gpa should be
> (86+74+88+77)/4*4/100
[1] 3.25To calculate weighted GPA, multiple each grade on a 4.0 scale by the weight of the course and then find the average.
The conversion of 0-100% grades to a 0.0-4.0 scale may be calculated differently at different institutions. You need to check with your institution to see exactly how they do it. However, almost no institution directly scales 0-100% to 0.0-4.0 proportionally. Instead, 0-100% is divided into discrete sections, each of which is then mapped to a specific point value.
The most common system in the United States uses sections of size 10% for grades of 60% or higher, and gives no points for grades lower than 60%, which are considered failing:
- 90-100% -> 4.0
- 80-89% -> 3.0
- 70-79% -> 2.0
- 60-69% -> 1.0
- 0-59% -> 0.0
Under this system, your grades would convert as follows:
- 86% -> 3.0
- 74% -> 2.0
- 88% -> 3.0
- 77% -> 2.0
And your weighted GPA would then be:
(45 * 3.0 + 30 * 2.0 + 45 * 3.0 + 60 * 2.0) / (45 + 30 + 45 + 60) = 2.5
Another common system uses sections of size 5% instead of 10%:
- 95-100% -> 4.0
- 90-94% -> 3.5
- 85-89% -> 3.0
- 80-84% -> 2.5
- 75-79% -> 2.0
- 70-74% -> 1.5
- 65-69% -> 1.0
- 60-64% -> 0.5
- 0-59% -> 0.0
Under this system, your grades would convert as follows:
- 86% -> 3.0
- 74% -> 1.5
- 88% -> 3.0
- 77% -> 2.0
And your weighted GPA would then (rounded to three digits after the decimal point) be:
(45 * 3.0 + 30 * 1.5 + 45 * 3.0 + 60 * 2.0) / (45 + 30 + 45 + 60) ≈ 2.417
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