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Math & School
Test Score Calculator — EZ Grader for Questions Right Out of Total
The fast questions-correct grader teachers and students reach for first
This is the test grade calculator — the digital version of the cardboard EZ Grader wheel you've seen on a teacher's desk. You feed it two numbers, the number of questions a student got right and the total number of questions, and it instantly returns the percent score, the matching letter grade, and a chart of how many wrong answers map to which percentage. It's built for the one job teachers and students do over and over: turn "18 out of 20" into "90%, an A" without doing the long division by hand for thirty papers.
The math is the percent-correct formula:
Score % = (correct ÷ total) × 100
You can enter it either way. If you graded by counting wrong answers instead — the way most teachers actually mark a stack of quizzes — the calculator does correct = total − wrong for you, so 2 wrong out of 20 lands on the exact same 90% = A as 18 right out of 20. That's the whole convenience of an EZ grader: mark the misses, and it figures the score.
A fully worked example. A US high schooler takes a 40-question biology test and misses 6. Correct = 40 − 6 = 34. Score = 34 ÷ 40 × 100 = 85%, which is a B on the standard scale. Miss only 3 and the score is 37 ÷ 40 = 92.5% — an A−/A depending on the cutoffs your school uses.
The letter grade comes from the percentage on the common US 10-point scale: 90–100 = A, 80–89 = B, 70–79 = C, 60–69 = D, below 60 = F (with optional plus/minus bands inside each tier). Schools vary, so treat the letter as a guide and follow your own syllabus's cutoffs.
This calculator also has an optional curve. Two kinds show up in American classrooms: a flat curve that adds a fixed number of points to everyone's percentage (everybody gets +5), and a top-score curve that scales the highest grade in the class up to 100% and bumps everyone by the same amount. Turn the curve off and you get the raw score; turn it on to see what the adjusted grade would be.
A word of warning that trips students up every term: percent score and GPA are not the same thing. This tool grades a single test by questions correct. It does not weight by credit hours the way a GPA does, and it is not the points-based weighting a full grade calculator uses for homework, quizzes, and finals. Use it for exactly what an EZ grader is for — scoring one test, fast.
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Calculator
Fill in the fields and click "Calculate" for instant results.
📰 Formula
• Score % = (correct ÷ total) × 100 • Or, from misses: correct = total − wrong, then score % = (correct ÷ total) × 100 • Flat curve: adjusted % = score % + curve points • Top-score curve: bonus = 100 − highest score in class; adjusted % = score % + bonus • Letter (10-point scale): 90+ = A, 80–89 = B, 70–79 = C, 60–69 = D, below 60 = F
📰 Formula
• Score % = (correct ÷ total) × 100 • Or, from misses: correct = total − wrong, then score % = (correct ÷ total) × 100 • Flat curve: adjusted % = score % + curve points • Top-score curve: bonus = 100 − highest score in class; adjusted % = score % + bonus • Letter (10-point scale): 90+ = A, 80–89 = B, 70–79 = C, 60–69 = D, below 60 = F
🧪 Worked examples
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Example 2
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Example 3
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Example 4
⚠️ Common mistakes
- Entering the number wrong in the "right" box (or vice-versa) — pick one mode and stick to it.
- Dividing by the wrong total when some questions are extra-credit or thrown out.
- Assuming every school uses the same cutoffs — an 89.5% may round to an A at one school and stay a B at another.
- Treating a single test's percent as a GPA — GPA is credit-weighted, this is not.
- Adding a curve to a score that's already curved, double-counting the bonus.
💡 Tips
- Grade by counting wrong answers — it's faster on a big stack, and this tool converts misses to a score for you.
- Use the how-many-wrong chart to tell students up front how many they can miss and still earn each grade.
- For a top-score curve, find the highest grade in the class first, then add (100 − that score) to everyone.
- Cap any curved score at 100% — a curve shouldn't push a grade above a perfect paper.
Embed this calculator on your site
Copy the code below and paste it into the HTML of your site or blog.
<iframe src="https://www.calcnimbus.com/embed/test-score-calculator" width="100%" height="500" frameborder="0" style="border:1px solid #eee;border-radius:12px"></iframe>
❓ Frequently asked questions
How do I calculate a test score percentage?
Divide the number of questions answered correctly by the total number of questions, then multiply by 100. Example: 18 ÷ 20 × 100 = 90%. If you counted the wrong answers instead, subtract them from the total first: 20 − 2 = 18 correct.
What is an EZ Grader?
An EZ Grader is the classic cardboard wheel teachers use to grade tests fast. You line up the total number of questions with how many a student missed and read off the percentage. This calculator does the same thing digitally and adds the letter grade and a full chart.
Why do 18 right out of 20 and 2 wrong out of 20 give the same grade?
Because they describe the identical paper. Correct = total − wrong, so 20 − 2 = 18 correct. Both work out to 18 ÷ 20 = 90%, an A. The calculator lets you enter it whichever way you graded.
What letter grade is each percentage?
On the common US 10-point scale: 90–100% is an A, 80–89% a B, 70–79% a C, 60–69% a D, and below 60% an F. Many schools add plus and minus bands inside each tier, and some use different cutoffs, so check your syllabus.
How do I grade a test with a curve?
A flat curve adds the same number of points to every score (for example, +5 to everyone's percentage). A top-score curve scales the highest grade in the class up to 100% and adds that same bonus to everyone. Turn the curve on in the calculator to see the adjusted score.
How many can I get wrong and still get an A?
On a 20-question test you can miss 2 and still score 90% (an A). On a 40-question test you can miss 4. The rule is: max misses for a 90% = total × 0.10. The how-many-wrong chart in this tool spells it out for your exact question count.
Is this the same as a GPA calculator?
No. This grades a single test by questions correct and gives a percent and letter. A GPA averages letter grades across courses weighted by credit hours. Use a GPA calculator for your transcript and this one for scoring one quiz or exam.
How do I handle extra-credit questions?
Decide whether extra-credit counts toward the total. If the base test is 50 points and a bonus question adds 2, you can either keep the total at 50 (so a perfect score with the bonus is 104%) or set the total to 52. Enter the total you intend to grade against.
Does the calculator round the percentage?
It shows the percent to one decimal so you can see scores like 92.5% clearly. Whether 89.5% rounds up to an A is a school policy decision — the tool reports the exact number and the letter from your cutoffs, and you apply any rounding rule your class uses.