What each question is worth on a 40-question test
100 ÷ 40 = 2.5, so each wrong answer takes 2.5 points off. An even number of wrong answers gives a whole percent (36 out of 40 is 90%); an odd number gives a half percent (35 out of 40 is 87.5%). The half percents are where grades get decided, because they sit right on the edge of the plus-minus letters.
Where the letter grades fall out of 40
On the standard scale an A is 36 to 40 right (up to 4 wrong), a B is 32 to 35, a C is 28 to 31, a D is 24 to 27, and 23 or fewer is an F. On the plus-minus scale an A+ needs 39 (97.5%), an A 38 (95%), and 36 or 37 is an A−. 35 out of 40, 87.5%, is a B+.
Worked example: 29 out of 40 and the half percent
11 wrong is 29 right: 29 × 2.5 = 72.5%. On the standard scale that is a C either way. On the plus-minus scale the exact 72.5% is a C−, because C starts at 73; a teacher who rounds to whole percents records 73% and a C. This chart shows the exact percent. To print the same chart with whole percents, rounded or never rounded up, open the grading chart set to 40 questions and pick the rule your school uses.
Grading a stack of 40-question tests
Print the chart and keep it next to the answer key: count the wrong answers, find the row, write the percent and letter. For tests with extra credit or half points, the grading calculator starts at 40 questions. For one score with uneven point values, like 36/42, use the percentage grade calculator.
Where the letter lines come from
The A–F column uses the standard scale that the School District of Palm Beach County and Roanoke County Public Schools publish: A 90–100, B 80–89, C 70–79, D 60–69, F below 60. The +/− column uses A+ from 97, A from 93 and A− from 90, and so on down to D− at 60. Schools set their own lines, so check your syllabus; the grading scale page compares published scales. Other test lengths: the grading chart for 1 to 100 questions.
40-question grading questions
What is 29 out of 40 as a grade?
29 out of 40 is 72.5%, a C on the standard scale. On the plus-minus scale it is a C−, because C starts at 73. A teacher who rounds to whole percents records 73%, which is a C.
How many questions can you miss on a 40-question test and get an A?
Four. 36 out of 40 is 90%, the lowest A on the standard scale (an A− on the plus-minus scale). For a full A on the plus-minus scale, from 93%, you can miss two: 38 out of 40 is 95%.
What is 34 out of 40?
34 out of 40 is 85%, a B on both the standard and the plus-minus scale. Each of the six wrong answers costs 2.5 points.