Formula
Score = (questions − wrong) ÷ questions × 100% How it works
Subtract the wrong answers from the total, divide by the total and multiply by 100. On a 40-question test, every question is worth 2.5%, so 6 wrong answers cost 15 points and leave 85%.
The letter grade uses a widely used US scale: 93% and up is an A, 90–92.9 A−, 87–89.9 B+, 83–86.9 B, 80–82.9 B−, and so on in 3- and 4-point steps down to 60 (D−). Below 60 is an F. Many teachers use a simpler 90/80/70/60 scale, so check the syllabus.
If questions carry different point values, enter total points and points lost instead — the arithmetic is identical.
Frequently asked questions
Does partial credit work?
Yes. Decimals are allowed, so 2.5 points lost on a 50-point quiz gives 95%.
What percentage is a B?
On the scale used here, 83–86.9% is a B, with B+ starting at 87% and B− at 80%.