In order to convert a letter grade to a percentage grade, you must first have a firm grasp of the grading scale that is being used in the particular class. Some teachers, courses, departments and schools use only straight letter grades A through F (skipping E, of course), while others use pluses and minuses for more precision. For the purposes of this "how to," we will assume the presence of minuses and pluses.
Things You'll Need
- class' grading scale
Converting a Letter Grade to a Percentage Grade
Memorize or refer to a written copy of the operative grading scale. A study out of Fairfax, Virginia determined that 33 of the top 45 high schools in the U.S. use the 10-point scale. This scale is often referred to as the "10 point scale" because each letter grade includes a ten point range within it.That scale is represented below is a version of the 10 point scale and will be used for the examples that follow.
A+ = 98-100%
A = 93-97%
A- = 90-92%
B+ = 88-89%
B = 83-87%
B- = 80-82%
C+ = 78-79%
C = 73-77%
C- = 70-72%
D+ = 68-69%
D = 63-67%
D- = 60-62%
F = 59% and below
Take the first test or paper you have already graded with a letter grade. Locate the specific letter grade you have given the test or paper 1 on the grading scale you are using. For instance, if this first exam or paper has been awarded an "A-", find the "A-" line on the grading scale. There are three numbers to which you could conceivably convert that single A- grade: 90%, 91% or 92%.
Determine how strong an A- that particular test or paper is. The conversion admittedly becomes a bit subjective here. You must decide whether that first test or paper is closer to a B+ or to an A. If your determination is that it is closer to an A, a 92% makes the most sense. If it seems closer to a B+, then a 90% is more appropriate. If neither the 90% nor the 92% fits, the 91% provides the middle option.
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