Test Calculator
Use our test calculator to grade exams fast. Choose a grade scale, enter total questions and wrong answers, and get your score and grade.
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What the Test Calculator does
You have a stack of tests to grade, or one of your own to score, and you would rather not do the same little division forty times over. So this calculator does it for you: tell it how many questions there were and how many were missed, and it hands back the percentage and a letter grade in one go.
Teachers use it as the fast lane through a pile of marking. Students use it to score a practice test the moment they put the pen down.
How to use the Test Calculator
- Grades Scale: pick the letter style you want, plain letters (A, B, C, D) or the plus and minus version.
- Number of Questions: how many questions the test had in total.
- Number of Wrong Answers: how many were missed.
Press Calculate, and you get the score as a percentage along with its letter grade.
How the Test Calculator works
The percentage is simply the share you got right, turned into a percent:
Score = (questions - wrong) ÷ questions × 100
So if 3 are wrong out of 20, that is 17 right, and 17 ÷ 20 × 100 = 85%. The calculator then reads that percentage off the grade scale you picked to land on the letter. Every question counts the same here, which is exactly what lets a single wrong-answer count grade the whole test.
A worked example
Say a quiz had 25 questions and a student missed 4.
That leaves 21 correct, so the score is 21 ÷ 25 × 100 = 84%. On the plain letter scale, 84% is a B. Miss two instead of four and it climbs to 92%, an A. Each question on a 25-item test is worth 4 percentage points, so every answer moves the needle by the same step.
The grade scale, and where it bends
This tool offers two letter styles. The plain one uses the familiar bands: the 90s are an A, the 80s a B, the 70s a C, the 60s a D, and below 60 is an F. The other adds pluses and minuses to the labels.
The percentage is the solid part. The letter is a convention, and conventions differ. Some schools start an A at 93 rather than 90, some use a flat 10-point scale with no pluses or minuses, and some weight certain questions more heavily than others. So treat the percentage as the fact and the letter as a guide, and when it counts, line it up with your own school's scale.
Who this is for
- Teachers grading a set of tests quickly, where a wrong-answer count beats adding up points one by one.
- Students scoring a practice exam the second they finish it.
- Anyone with a quiz in hand who wants the percentage and the letter without reaching for a calculator app.
Grading a whole course from weighted homework, quizzes, and exams instead? That is the Grade Calculator. Working out what you need on a final? The Final Grade Calculator has it.
Things to keep in mind
- Every question is treated as equal. This works when each question is worth the same. If some questions carry more points, or there is partial credit, the percentage here will not match.
- The letter follows a standard scale. Your school may draw the lines differently, so check its grading chart for anything official.
- Wrong means fully wrong. Half-right answers and partial marks are not part of a simple wrong-answer count.
- Double-check the total. The whole score hangs on the number of questions, so make sure that figure is right before you trust the grade.
Questions people ask
How do I calculate a test grade from wrong answers?
Subtract the wrong answers from the total to get the number correct, divide by the total, and multiply by 100. This tool does that and reads off the letter grade for you.
What letter grade is my score?
It depends on the scale. On the standard one, the 90s are an A, the 80s a B, the 70s a C, the 60s a D, and below 60 is an F. Your school may set the lines a little differently.
Does this work if questions are worth different points?
No. It assumes every question carries equal weight. For a test with weighted questions or partial credit, divide the points you earned by the points possible instead.
What counts as a good score on a test?
It depends on the class and the scale. On the standard scale, 90% and up is an A, but your syllabus sets the bar that actually counts.
Can students use this, not just teachers?
Yes. It is handy for scoring a practice test right after you finish, so you know where you stand before the real thing.
Ajay Yadav is a youth development practitioner and graduate of Development Studies. He serves as an IDA Youth Champion with the World Bank, representing South Asian youth on employment and job creation initiatives, and co-founded Youthive in 2023 to bridge academic learning and workplace readiness through entrepreneurial skill building. At Eon Tools, he reviews education tools.