Calculator
Multiple-choice score calculator
Right, wrong and blank answers, with your exam's negative marking: 3 or 4 options, true or false, or whatever your exam rules say. You get the score out of 10 and out of any maximum you pick.
Your score
- Net correct
- 52 of 100
- Net percentage
- 52 %
- Taken off per wrong answer
- 0.33
The sum runs in your browser. Nothing is sent or stored.
The formula for multiple-choice negative marking
Each right answer adds one, each wrong answer takes off a fraction of one, and each blank adds nothing. What is left is divided by the number of questions and scaled to the exam's maximum.
Score = (R − W × p) ÷ N × 10
R: right answers
Questions answered correctly.
W: wrong answers
Questions answered incorrectly. Blanks are not wrong answers.
N: total questions
Right, wrong and blank together. Blanks take nothing off, but they do count here.
p: what each wrong answer takes off
In the standard formula, 1/(n − 1), where n is the number of options per question.
Why 1/(n − 1)? Because it is the figure that leaves someone guessing every answer at zero on average. With 4 options, blind guessing hits one in four: one right and three wrong, and three wrong answers at a third each cancel that one right answer. The SAT used it until 2016, taking a quarter point off for each wrong answer on five-option questions.
| Options | Each wrong answer takes off | Wrong answers that cancel one right answer |
|---|---|---|
| 2 (true or false) | 1 (1) | 1 wrong answer |
| 3 | 1/2 (0.5) | 2 wrong answers |
| 4 | 1/3 (0.33) | 3 wrong answers |
| 5 | 1/4 (0.25) | 4 wrong answers |
Three worked examples
A 100-question exam with 4 options
60 right, 24 wrong and 16 blank. Each wrong answer takes off 1/3, so the 24 wrong answers cost 8 marks: 60 − 8 = 52 net correct out of 100. Score: 5.2 out of 10. With no penalty it would have been 6.
A 50-question exam with 3 options
With three options the penalty rises to 1/2 per wrong answer. 38 right and 10 wrong, with 2 left blank: the wrong answers cost 5, leaving 33 net out of 50 and a score of 6.6. With nothing taken off, 7.6.
True or false, 50 questions
With two options, each wrong answer cancels a whole right one. 30 right, 12 wrong and 8 blank give 30 − 12 = 18 net: a 3.6. With no penalty it would be 6. On true or false, blind guessing is expensive.
Guess or leave it blank?
With standard negative marking, guessing blindly among all the options neither gains nor loses on average: that is what the formula is built for. The sums change as soon as you can rule out an option.
With 4 options, if you rule one out and pick among the remaining three, you are right one time in three. On average you gain 1/3 of a mark and lose 2/3 × 1/3 = 2/9, so guessing is worth a little over a tenth of a mark per question. Rule out two and the edge grows to 1/3.
If you cannot rule any out, leaving it blank and guessing blindly are worth the same on average, but guessing adds risk. And if your exam takes off more than the standard formula, the sums change: try your own penalty in the calculator.
Frequently asked questions
Do blank answers lose marks?
Not with the standard formula: they score zero. They do count in the total, so leaving many blank lowers the score even though nothing is taken off. If your exam also penalises unanswered questions, its rules or course guide will say so.
Why does a wrong answer cost more with 3 options than with 4?
Because blind guessing hits more often. With 3 options, one random answer in three is right, so to stop guessing from paying off each wrong answer has to cancel half a mark. With 4 a third is enough, and with 5 a quarter.
Can the score be negative?
Yes, when the wrong answers take off more than the right ones add. The calculator shows the number as it is, sign included. Some exams round it up to zero; how yours treats it is in its rules.
My exam takes off 0.25 per wrong answer. How do I enter that?
Choose "Other penalty" and type 0.25 or 1/4. It is read as the share of one right answer that each wrong answer takes away. If your rules say three wrong answers cancel one right answer, type 1/3.
What if the exam is marked out of 20 or 100?
Change the maximum score. The calculator always gives the score out of 10 and, under it, the same proportion out of the maximum you set, whether that is 20, 60 or 100.
Which exams does it work for?
Any multiple-choice exam that adds for right answers and subtracts for wrong ones. What changes from one to the next is how much a wrong answer costs and whether blanks are penalised: check your exam rules or course guide and enter that in the calculator.
See this score before the exam
The calculator tells you what you scored. Knowing what you will score takes practice with questions from your own syllabus. CanQuiz makes quizzes from your notes, PDFs or photos and lets you retry the ones you miss until you get them: see how to turn your notes into a quiz or how to set up a mock exam from your own material.
Practise with your own syllabus
Make a quiz from your notes and retry the questions you miss until exam day.
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