How to Grade a Test
Grading a test by hand can eat up a lot of time, especially when you have a whole stack of papers or you are trying to work out your own result. The good news is that it only takes a bit of basic math. Count how many answers were right, compare that to the total, and turn the result into a percentage. From there, you can match it to a letter grade.
Grading rules differ from country to country, and even from school to school. The US, the UK and Canada each use their own systems, so a score that earns a “B” in one place might be a different grade somewhere else. Use the calculator to get your result in seconds, then read on to see exactly how the numbers are worked out.
Advanced options
Anything below the D cutoff is an F.
How to calculate a test score
A test score shows how well a student did compared with the total number of questions or points available. It works for a quiz, an exam or any assignment, whether you are the teacher marking a stack of papers or the student checking your own result. First find the percentage of correct answers. Then convert that percentage to a letter grade using your grading scale.
The test score formula
The formula is the same for any test with a fixed number of questions or points. Divide the correct answers by the total, then multiply by 100.
Percentage score = (Correct answers ÷ Total questions) × 100Example: a test has 25 questions and a student answers 20 correctly.
(20 ÷ 25) × 100 = 80%The student scored 80%.
If you only know how many answers were wrong, subtract them from the total first. With 5 wrong answers on a 25-question test, the student has 25 − 5 = 20 correct answers, and the calculation continues exactly as above.
Converting a percentage to a letter grade
Once you have the percentage, compare it with your school’s grading scale. A common scale looks like this:
| Percentage | Letter grade |
|---|---|
| 90% – 100% | A |
| 80% – 89% | B |
| 70% – 79% | C |
| 60% – 69% | D |
| Below 60% | F |
Not every institution follows this exactly. Some add plus and minus grades, such as B+ or A−, and others set a different passing mark. Always adjust the scale to match your own class or school. The calculator lets you do that in the Advanced options.
Test grade calculator: how to use it
A test grade calculator does the math for you:
- Enter the total number of questions or points on the test.
- Enter how many were answered incorrectly. If it is easier, switch to “Correct answers” and enter those instead.
- The calculator works out the percentage and shows the matching letter grade.
For a quick count while marking papers, press “+1 Incorrect” each time you find a wrong answer and watch the score update. Letting the tool handle the calculations saves time and reduces human error in grading.
Advanced options
Many teachers need more flexibility than a basic scale offers. Open Advanced options to:
- Set your own cutoffs. Change the percentage needed for an A, B, C or D to match your school.
- Set a custom passing mark. For example, treat 50% as a pass instead of the usual 60%.
- Use plus and minus grades. Turn on B+, B and B− style grades inside each letter band.
The display options above the results help too. Turn decimals off to round scores to a whole number, or turn on the graph to see the correct and incorrect answers at a glance.
Reading your test results
After you enter the numbers, you will see the percentage and the letter grade together. For example, 18 correct answers out of 20 equals 90%, which is an “A” on most scales. If your policy calls for it, you can round scores up or down, or apply other rules before finalizing the grade. This makes it quick to produce consistent, reliable results for a whole class.
Score chart for a 20-question test
Here is how each score looks on a 20-question test using the common scale. Every question is worth 5% of the total.
| Correct | Incorrect | Percentage | Grade |
|---|---|---|---|
| 20 | 0 | 100% | A |
| 19 | 1 | 95% | A |
| 18 | 2 | 90% | A |
| 17 | 3 | 85% | B |
| 16 | 4 | 80% | B |
| 15 | 5 | 75% | C |
| 14 | 6 | 70% | C |
| 13 | 7 | 65% | D |
| 12 | 8 | 60% | D |
| 11 | 9 | 55% | F |
| 10 | 10 | 50% | F |
How much is each question worth?
Divide 100 by the number of questions to see how many percentage points each wrong answer costs.
| Questions on the test | Each question is worth |
|---|---|
| 10 | 10% |
| 20 | 5% |
| 25 | 4% |
| 40 | 2.5% |
| 50 | 2% |
| 100 | 1% |
Frequently asked questions
How do you calculate a test score as a percentage?
Divide the number of correct answers by the total number of questions, then multiply by 100. If a student gets 20 correct out of 25, the score is 20 ÷ 25 × 100 = 80%.
How do you grade a test when you only know the wrong answers?
Subtract the number of wrong answers from the total to get the number of correct answers, then use the same percentage formula. A 25-question test with 5 wrong answers has 20 correct answers, which is 80%.
What percentage is an A?
On the common scale, an A is 90% to 100%. Some schools use a different cutoff, so check the scale used in your class.
Can I use the calculator for points instead of questions?
Yes. Enter the total points available as the total and the points lost as the incorrect amount. The percentage is calculated the same way.
How do I change the grading scale?
Open Advanced options in the calculator. You can edit the cutoffs for A, B, C and D, set your own passing mark and turn on plus and minus grades.
Is 70% a passing grade?
It depends on the school. On the common scale 70% is a C, and many schools treat 60% as the lowest passing score, while some require 70%. Check your own grading policy.