To grade a test, divide the number of correct answers by the total number of questions and multiply by 100. As a formula:
Score = (correct ÷ total) × 100
The number wrong is simply the total minus the number correct, so you can count up from a blank paper or down from a perfect one and land on the same score. The EZ grader does the division for you and also prints a full chart, but the method is quick once you see it.
A worked example
Say a quiz has 25 questions and a student gets 3 wrong. That leaves 22 correct:
- Correct: 25 − 3 = 22
- Score: 22 ÷ 25 × 100 = 88%
- Grade: 88% falls in the 80-89 band, so it is a B.
Change the total and the same three wrong answers are worth more or less. Three wrong out of 10 is only 70% (a C), because each question is worth 10 points instead of 4.
The letter-grade scale
Once you have the percentage, match it to a letter. The standard US scale is:
| Score | Grade |
|---|---|
| 90-100% | A |
| 80-89% | B |
| 70-79% | C |
| 60-69% | D |
| Below 60% | F |
Some schools add pluses and minuses, and a few use different cut-offs, such as 93 for an A. Use the scale your school or department publishes; the bands above are the most widely used default.
Why a grading chart is faster
Grading one paper by hand is easy. Grading thirty is where the division adds up. A grading chart solves that: it lists every possible number wrong for a given test length, next to its score and letter grade. Print it once for a 25-question test and every paper takes a glance, no calculator.
That is what the plastic grading slide-cards on teachers’ desks do, and what the EZ grader reproduces for any number of questions. Here is the top of the chart for a 20-question test:
| # Wrong | Score | Grade |
|---|---|---|
| 0 | 100% | A |
| 1 | 95% | A |
| 2 | 90% | A |
| 3 | 85% | B |
| 4 | 80% | B |
| 5 | 75% | C |
How this differs from other grade tools
This is a raw-score grader: questions right and wrong to a percentage. It is not the same as two related jobs:
- A weighted grade calculator combines categories like homework, quizzes and exams by their weight to give a course grade.
- A final grade calculator works out the score you need on a final exam to reach a target overall grade.
Use the EZ grader when you have a single test and just need the percentage and letter grade from the number correct or wrong.
