Test Score Calculator

Input Mode

Grading Scale

Total Questions

Quick presets:

Number of Wrong Answers

Use + / - buttons for rapid grading

Bonus / Extra Credit Questions

Optional — adds to your correct count (can push score above 100%)

Desired Grade (Reverse Calculator)

See how many wrong answers you can afford

Enter Your Test Details

Fill in the total questions and wrong answers (or points earned) above to instantly see your percentage score, letter grade, and full grade breakdown table.

Last updated October 20, 2018

Convert wrong answers or earned points into a percentage score and letter grade instantly

Whether you are a student checking your test results before official grades are posted, a teacher grading a stack of papers quickly, or a parent helping a child understand their academic performance, a reliable test score calculator saves time and removes guesswork. Our free Test Score Calculator handles everything from a simple ten-question quiz to a comprehensive hundred-point exam with extra credit, giving you the percentage score and letter grade in real time. Understanding your test score goes beyond just knowing how many questions you got right. The percentage score tells you where you stand on a universal scale, while the letter grade communicates that performance in the language most schools and universities use. A score of 18 out of 20, for example, translates to 90%—solidly in the A range—while 14 out of 20 is 70%, landing at a C. Converting these fractions mentally can be error-prone, especially under stress or when grading dozens of papers. This calculator does the math instantly and accurately. The tool supports two input modes to match how you think about the test. In Wrong Answers mode, you enter the total number of questions and how many were answered incorrectly; the calculator determines how many were correct and computes the percentage. In Points Earned mode, you enter the raw score out of a maximum point value, which is ideal for essay exams, weighted tests, or any situation where questions are not all worth one point. Both modes support bonus or extra credit points, allowing scores above 100%. Two grading scales are available. The Simple scale (A, B, C, D, F) uses the classic five-tier system that is widely used in primary and secondary education: A for 90% and above, B for 80–89%, C for 70–79%, D for 60–69%, and F below 60%. The Extended scale adds plus and minus modifiers (A+, A, A-, B+, B, B-, C+, C, C-, D+, D, D-, F), providing finer granularity that is standard in many high schools and most universities. For teachers grading a batch of tests, the quick-increment buttons next to the wrong answers field let you tap plus or minus to step through wrong answer counts one at a time without retyping. Preset buttons for common question totals (10, 20, 25, 50, 100) let you switch the exam size with a single click. The full grade breakdown table below the main result shows every possible wrong-answer count from zero to the total, along with the resulting percentage and letter grade—a handy reference that replaces printed grade charts. The reverse calculator answers the question every student asks before a big exam: how many questions can I get wrong and still earn a B? Enter your desired target grade alongside the total question count, and the tool calculates the maximum number of wrong answers you can afford while still achieving that grade. This is equally useful for planning study strategies and for understanding the margin between grade boundaries. All calculations happen instantly in your browser. No data is sent to any server, and the results update automatically as you type. When you are done, you can export the full results—including the grade breakdown table—to a CSV file for record-keeping or sharing.

Understanding Test Scores and Grading

What Is a Test Score Percentage?

A test score percentage expresses your performance as a proportion of the maximum possible points, multiplied by 100. If you answer 17 questions correctly out of 20, your percentage is (17 ÷ 20) × 100 = 85%. This standardized format makes it easy to compare results across exams with different numbers of questions or point values. A percentage score removes the ambiguity of raw fractions—85% communicates performance clearly regardless of whether the test had 20 questions or 200. When bonus points are included, the percentage can exceed 100%, which some teachers allow to reward exceptional effort or make up for a poor earlier performance.

How Is a Letter Grade Calculated?

A letter grade is assigned by comparing the percentage score against a grading scale's defined thresholds. In the standard simple scale, 90% and above earns an A, 80–89% a B, 70–79% a C, 60–69% a D, and below 60% an F. The extended scale subdivides each letter with plus and minus modifiers: an A+ requires 97% or higher, while an A- spans 90–92.99%. Different institutions use slightly different thresholds—some give A+ only for 98%+ or even reserve it exclusively for a perfect 100%—so it is always worth checking your school's official policy. This calculator uses the thresholds shown in the grade breakdown table, which are consistent with the most widely published academic standards in the United States.

Why Does Your Test Score Matter?

Test scores directly affect course grades, GPA, academic standing, scholarship eligibility, and in some cases college admissions or professional certification. Understanding your score immediately after a test lets you gauge whether you are on track, whether you need to seek help, and how much effort to invest in upcoming assignments or exams. For teachers, fast and accurate grading improves feedback turnaround—research consistently shows that prompt feedback accelerates learning. Knowing the grade distribution across all possible wrong-answer counts also helps educators calibrate the difficulty of future exams: if a score of 16 correct out of 25 still earns a C, the test may need revision. Tracking test scores over time can reveal subject-specific weaknesses, study habit patterns, and the effectiveness of tutoring or additional practice.

Limitations and Considerations

This calculator uses fixed percentage thresholds to assign letter grades. In practice, grading scales vary: some teachers curve grades based on class performance, use non-standard thresholds, or apply weighted scoring where some questions count more than others. If your instructor curves results or uses a scale different from the standard A=90%+, the letter grade shown here may differ from your official grade. The tool also does not account for partial credit, which is common in math and science exams where showing work can earn points even when the final answer is wrong. For exams that use negative marking (deducting points for wrong answers), the Points Earned mode is the appropriate input method—simply enter your net score after deductions as the points earned value.

Test Score Formulas

Percentage Score

Score % = (Correct Answers / Total Questions) × 100

Divides the number of correct answers by the total number of questions and multiplies by 100 to express performance as a percentage.

Score from Wrong Answers

Score % = ((Total − Wrong) / Total) × 100

An equivalent approach that subtracts wrong answers from the total to determine correct answers, then converts to a percentage.

Points Needed for Target Grade

Points Needed = (Target % / 100) × Total Points − Current Points

Calculates how many additional points are required to reach a target percentage grade on a cumulative or multi-part assessment.

Maximum Wrong Answers for Target Grade

Max Wrong = Total − ceil(Target % / 100 × Total)

Determines the maximum number of questions you can answer incorrectly while still achieving a minimum target percentage grade.

Test Score Reference Tables

Test Score to Letter Grade Conversion

Standard US grading scale mapping percentage scores to letter grades. The simple scale uses 5 grades (A–F); the extended scale adds +/- modifiers.

Percentage	Simple Grade	Extended Grade	GPA Equivalent
97–100%	A	A+	4.3
93–96%	A	A	4.0
90–92%	A	A-	3.7
87–89%	B	B+	3.3
83–86%	B	B	3.0
80–82%	B	B-	2.7
77–79%	C	C+	2.3
73–76%	C	C	2.0
70–72%	C	C-	1.7
60–69%	D	D+/D/D-	1.3–0.7
0–59%	F	F	0.0

Common Test Score Types Comparison

Different scoring methods used in standardized and classroom testing, and how they differ from simple percentage scores.

Score Type	Scale	What It Measures	Example Tests
Percentage	0–100%	Proportion of correct answers	Classroom quizzes and exams
Percentile Rank	1st–99th	Performance relative to peers	SAT, ACT, GRE, state assessments
Scaled Score	Varies	Difficulty-adjusted performance	SAT (200–800), GRE (130–170)
Stanine	1–9	Standardized nine-point scale	Achievement tests, aptitude tests
Z-Score	−3 to +3	Standard deviations from mean	Research, statistical analysis
Grade Equivalent	K–12+	Grade level of typical performance	Reading assessments, MAP tests

Test Score Worked Examples

Calculate Percentage from 42 out of 50 Correct

A student answers 42 questions correctly on a 50-question multiple-choice exam.

Number correct: 50 − 8 wrong = 42 (or given directly)

Percentage: (42 / 50) × 100 = 84%

Look up 84% on the extended grading scale

84% falls in the B range (83–86%)

GPA equivalent: 3.0

A score of 42/50 earns an 84% — a solid B. The student could miss at most 7 questions to earn a B+ (86%), or needed just 3 more correct answers (45/50 = 90%) for an A-.

Score Needed on Final to Earn an A in the Course

A student has 340 out of 400 points so far (85%). The final exam is worth 100 points. They need 90% overall (450/500) for an A-.

Total points possible in course: 400 + 100 = 500

Points needed for 90% overall: 0.90 × 500 = 450

Points already earned: 340

Points needed on final: 450 − 340 = 110

But the final is only worth 100 points maximum

110 > 100, so an A- is not achievable

The student needs 110 points on a 100-point final, making an A- impossible. Their maximum possible overall grade is (340 + 100) / 500 = 88%, which is a B+. They should aim for the highest possible score to secure a strong B+.

Using the Reverse Calculator: How Many Can I Miss for a B?

A 25-question exam uses the standard grading scale. The student wants to know the maximum wrong answers allowed for a B (80%).

Minimum correct for 80%: ceil(0.80 × 25) = 20 correct

Maximum wrong: 25 − 20 = 5 questions

Verify: (20 / 25) × 100 = 80% → B- on extended scale

For a solid B (83%): need ceil(0.83 × 25) = 21 correct → max 4 wrong

The student can miss at most 5 questions to earn a B- (80%) or 4 questions for a solid B (83%). Missing 6 or more drops the score to 76% (C+).

How to Use the Test Score Calculator

Choose Your Input Mode

Select 'Wrong Answers' if you know how many questions were missed, or 'Points Earned' for raw-score or weighted exams. Also choose your grading scale — Simple (A/B/C/D/F) or Extended (with +/- modifiers).

Enter the Test Details

In Wrong Answers mode, type the total number of questions and the number incorrect. Use the quick preset buttons (10, 20, 25, 50, 100) to set common totals, and the +/- buttons to step through wrong answer counts one at a time — great for grading a stack of tests.

Review Your Score and Grade

Your percentage score, letter grade, and correct/total fraction appear instantly. The donut chart and score-position bar show where your score sits on the grading scale. Bonus points can be added to credit extra-credit questions.

Use the Grade Table and Reverse Calculator

Scroll down to see every possible wrong-answer count and its resulting grade — highlighted on the row matching your current score. Use the Desired Grade dropdown to find out the maximum number of questions you can miss and still achieve your target grade.

Frequently Asked Questions

How do I calculate a test score percentage?

Divide the number of correct answers by the total number of questions, then multiply by 100. For example, if you answered 17 out of 20 questions correctly, the calculation is (17 ÷ 20) × 100 = 85%. If you prefer to think in terms of wrong answers, subtract them from the total first: 20 – 3 wrong = 17 correct, then 17 ÷ 20 × 100 = 85%. This calculator handles both approaches automatically — just choose your input mode and type in the numbers.

What is the difference between the Simple and Extended grading scales?

The Simple scale uses five letter grades: A (90–100%), B (80–89%), C (70–79%), D (60–69%), and F (below 60%). It is commonly used in primary school and some secondary school settings. The Extended scale adds plus and minus modifiers to each letter, creating 13 grade levels from A+ (97–100%) down to F (below 60%). The extended scale is standard in most high schools and universities and gives a finer measure of performance — the difference between a strong B+ (87–89%) and a solid B (83–86%) is meaningful when calculating GPA.

How does the reverse calculator work?

The reverse calculator tells you the maximum number of wrong answers you can afford while still earning a specific letter grade. It works by finding the minimum percentage required for your desired grade, then calculating how many correct answers that minimum requires. For example, on a 25-question test, to earn a B (80%) you need at least 20 correct answers, meaning you can miss at most 5 questions. Select your desired grade from the dropdown and the answer updates instantly. This is useful for pre-exam planning — you can see exactly how much margin you have before dropping to a lower grade.

Can my score be higher than 100%?

Yes, if your teacher offers bonus or extra credit questions, your effective correct count can exceed the total number of required questions. In the calculator, enter the number of bonus questions you answered correctly in the Bonus / Extra Credit field. The calculator adds them to your correct count before computing the percentage, so a score of 22 correct out of 20 questions (with 2 bonus) would yield 110%. Many grading systems allow this to reward exceptional effort, though some cap the final grade at 100% — check with your instructor if you are unsure.

What does the grade breakdown table show?

The grade breakdown table lists every possible wrong-answer count from zero (a perfect score) up to the total number of questions. For each row, it shows how many questions would be correct, the resulting percentage, and the letter grade. The row matching your current wrong-answer count is highlighted for easy reference. This table is especially useful for teachers who want to see the full distribution of possible outcomes before grading, and for students who want to understand the boundaries between grade levels on a specific exam.

How do I use this calculator to grade multiple tests quickly?

Set the total number of questions using the preset buttons (or type it in), then use the plus button next to the wrong-answers field to step through counts one at a time. After recording each grade, tap the minus button if needed or hit Reset to return to zero wrong answers. This workflow mimics the QuickGrade-style rapid grading approach where a teacher holds the paper, counts the marks, and taps plus once for each wrong answer to see the grade immediately. The grade breakdown table also allows you to look up any wrong-answer count without changing the inputs at all.

Test Score Calculator