Some teachers use Excel worksheets to calculate grades for students. Doing so is quite easy, as you sum the results of various student benchmarks (quizzes, tests, assignments, etc.) and then apply whatever calculation is necessary to arrive at a final numeric grade.

If you do this, you may wonder how you can convert the numeric grade to a letter grade. For instance, you may have a grading scale defined where anything below 52 is an F, 52 to 63 is a D, 64 to 74 is a C, 75 to 84 is a B, and 85 to 99 is an A.

There are several ways that a problem such as this can be approached. First of all, you could use nested IF functions within a cell. For example, let’s assume that a student’s numeric grade is in cell G3. You could use the following formula to convert to a letter grade based on the scale shown above:

```=IF(G3<52,"F",IF(G3<64,"D",IF(G3<75,"C",IF(G3<85,"B","A"))))
```

While such an approach will work just fine, using nested IF functions results in the need to change quite a few formulas if you change your grading scale. A different approach that is also more flexible involves defining a grading table and then using one of the LOOKUP functions (LOOKUP, HLOOKUP, and VLOOKUP) to determine the proper letter grade.

As an example, let’s assume that you set up a grading table in cells M3:N7. In cell M3 you place the lowest possible score, which would be a zero. To its right, in cell N3, you place the letter grade for that score: F. In M4 you place the lowest score for the next highest grade (53) and in N4 you place the corresponding letter grade (D). When you are done putting in all five grade levels, you select the range (M3:N7) and give it a name, such as GradeTable. (How you name a range of cells is covered in other issues of ExcelTips.)

Now you can use a formula such as the following to return a letter grade:

```=VLOOKUP(M22,GradeTable,2)
```

The beauty of using one of the LOOKUP functions in this manner is that if you decide to change the grading scale, all you need to do is change the lower boundaries of each grade in the grading table. Excel takes care of the rest and recalculates all the letter grades for your students.

When you put together your grading table, it is also important that you have the grades-those in the GradeTable-go in ascending order, from lowest to highest. Failure to do so will result in the wrong formula results using VLOOKUP.