Every number wrong comes with its percent and letter on one sheet, covering tests of 10 to 50 questions.
Letter scale:
Letter scale: plus-minus
10 questions
Wrong
Percent
Grade
0
100%
A+
1
90%
A−
2
80%
B−
3
70%
C−
4
60%
D−
5+
under 60%
F
12 questions
Wrong
Percent
Grade
0
100%
A+
1
91.7%
A−
2
83.3%
B
3
75%
C
4
66.7%
D
5+
under 60%
F
15 questions
Wrong
Percent
Grade
0
100%
A+
1
93.3%
A
2
86.7%
B
3
80%
B−
4
73.3%
C
5
66.7%
D
6
60%
D−
7+
under 60%
F
20 questions
Wrong
Percent
Grade
0
100%
A+
1
95%
A
2
90%
A−
3
85%
B
4
80%
B−
5
75%
C
6
70%
C−
7
65%
D
8
60%
D−
9+
under 60%
F
25 questions
Wrong
Percent
Grade
0
100%
A+
1
96%
A
2
92%
A−
3
88%
B+
4
84%
B
5
80%
B−
6
76%
C
7
72%
C−
8
68%
D+
9
64%
D
10
60%
D−
11+
under 60%
F
30 questions
Wrong
Percent
Grade
0
100%
A+
1
96.7%
A
2
93.3%
A
3
90%
A−
4
86.7%
B
5
83.3%
B
6
80%
B−
7
76.7%
C
8
73.3%
C
9
70%
C−
10
66.7%
D
11
63.3%
D
12
60%
D−
13+
under 60%
F
40 questions
Wrong
Percent
Grade
0
100%
A+
1
97.5%
A+
2
95%
A
3
92.5%
A−
4
90%
A−
5
87.5%
B+
6
85%
B
7
82.5%
B−
8
80%
B−
9
77.5%
C+
10
75%
C
11
72.5%
C−
12
70%
C−
13
67.5%
D+
14
65%
D
15
62.5%
D−
16
60%
D−
17+
under 60%
F
50 questions
Wrong
Percent
Grade
0
100%
A+
1
98%
A+
2
96%
A
3
94%
A
4
92%
A−
5
90%
A−
6
88%
B+
7
86%
B
8
84%
B
9
82%
B−
10
80%
B−
11
78%
C+
12
76%
C
13
74%
C
14
72%
C−
15
70%
C−
16
68%
D+
17
66%
D
18
64%
D
19
62%
D−
20
60%
D−
21+
under 60%
F
There's no affiliation with E-Z Grader. The formula and scale here match those used by the calculator: right ÷ questions × 100, with the letter based on the exact percent.
A passing D− (60%) lets you miss 4 questions on a 10- or 12-question quiz, or 20 on a 50-question test.