Test percentage calculator with negative marking

In Iran's national university entrance exam (Konkur), each correct answer earns three points and each wrong answer loses one, so every three wrong answers cancel one right answer. A question you leave blank is zero, not negative. Because a correct answer is worth three points, the denominator is three times the number of questions.

Example: mathematics has 30 questions; you answered 18 correctly, 6 wrongly and left 6 blank. The numerator is 3 × 18 minus 6, which is 48, and the denominator is 3 × 30, which is 90. Your percentage is 48 ÷ 90 × 100 = 53.33. Had you left those 6 wrong questions blank, it would have been 60; so the wrong answers cost you 6.67 percentage points.

If you count all the questions together without weights, you get 50.83 percent; the calculator shows both numbers. Take the weights from the exam's own guide booklet: in the Konkur, each subject's weight depends on the exam group and field of study.

With four options and one-third negative marking, a completely blind guess neither helps nor hurts on average: a one-in-four chance of three points and a three-in-four chance of minus one add up to zero; it only makes the result more volatile. But if you can rule out one option with certainty, guessing among the remaining three helps on average.

That's why the “wrong answers cost … points” line under each subject in the calculator matters: if, over several tests in a row, wrong answers take a large share of your percentage, most of your guesses come from not knowing rather than from ruling options out.

If you run mock exams for a class or a tutoring centre, Porsino's Online exam builder lets you set the negative marking for each question and grades automatically. Each person's report card shows correct, wrong and blank answers, the negative marks, the percentage, the rank and a table per topic. For term and cumulative GPA, see the GPA calculator for details.