We can use Excel’s LOOKUP function to quickly convert exam or test scores to letter grades like A+ or F. In this article, let me explain the process and necessary formulas. I will also share a technique to calculate letter grades from test scores using percentiles.
Step 1: Set up a Mapping Table for Letter Grade & Scores
In your workbook, set up a mapping (or lookup) table like this to map out each of the letter grades to the test score boundary.
- When setting up the mapping table, make sure to start from lower score to higher score (for ex: 0 to 100)
- For each grade, just specify the lower boundary value. So for example, Grade F begins from 0, Grade B- begins from 65
Step 2: Calculate the letter grades using LOOKUP function
For this you need all the test scores for your students. Let’s say you have the test scores in column C, from cell C4. In an adjacent column, you can calculate the letter grade using the below LOOKUP formula.
=LOOKUP(C4,$G$6:$G$16,$F$6:$F$16)In this formula:
- First value (C4) refers to the score for which you need the letter grade
- Second value ($G$6:$G16) is the “scores from” column of your mapping table set up in Step 1.
- Third value ($F$6:$F$16) is the “letter grade” column of your mapping table.
Once you have a result for the first test score, drag the formula down to see letter grades for all students.
How to get Letter Grades from Percentiles (relative grading)
Sometimes you may want to calculate the letter grade from the percentile of the test score. This sort of thing is also called relative grading (RG). To do this, we can use the PERCENTILERANK functions of Excel.
Here is a 3 Step process for that:
Step 1: Set up a percentile-wise mapping table for letter grades
In your worksheet, set up a mapping table for letter grades like this:
Step 2: Calculate the Percentiles for each test score
Let’s say you have test scores in column C, in the range C4:C43.
In column D, write the formula =PERCENTRANK.INC($C$4:$C$43,C4) to calculate the percentile of test score in first cell against all scores. The result of this would be a percentile from 0% to 100% (both inclusive).
When you get the result for first cell, drag the formula down to fill up the rest.
Tip: If you want to calculate the percentile by excluding 0th and 100th percentiles, use the PERCENTILE.EXC function instead.
Step 3: Convert Percentiles to Letter Grade
For this, we can use the LOOKUP function again. In column E use the below function:
=LOOKUP(D4,$H$6:$H$16,$G$6:$G$16)In the above formula:
- First value (D4) refers to the percentile we calculated in step 2.
- Second value ($H$6:$H16) is the “percentile from” column of your mapping table set up in Step 1.
- Third value ($G$6:$G$16) is the “letter grade” column of your mapping table.
Download Test Score to Letter Grade Calculation Template
I made a quick Excel template to calculate letter grades from your test / exam marks. Just plug-in your values and see the results instantly. Download the template here.
Bonus: These formulas work in Google Sheets too!
That is right. All these formulas will work exactly same with Google sheets too. Here is a Google Sheets template if you need some help.
Things to keep in mind when calculating letter grades
Do take these cautions when calculating alphabetic letter grades from your exam marks.
- Mapping table setup: your letter grade mapping table needs to be from lowest marks / scores to highest. Just specify the lower boundary for each letter grade.
- For example, if grade F is from exam score 0 to 35, then write 0.
- If grade B+ is from 80 to 85, then write 80
- Clean up your data: If your test score data has missing values (for example, absent or hyphens) then the LOOKUP formula will give #N/A error. So clean up your data before you apply the LOOKUP function.
Next steps:
Now that you have calculated the letter grades, you may want to see the distribution of your student grades or understand which students are failing and need help. Use below Excel concepts & resources to do that.
