Test Score Calculator

A raw test score is simply questions correct divided by total questions, times 100. The letter grade is a separate convention layered on top, and it varies by institution — the widely used scale puts A at 93 and above, B at 83, C at 73, and D at 63, with plus and minus bands at the edges. Some schools use a straight 90/80/70/60 scale, which shifts every boundary.

That's 84%, a B on the standard scale — 8 questions missed. To reach 90% on a 50-question test you'd need 45 correct, so you were 3 questions short. Notice how much each question is worth: on a 50-question test every item moves your score 2 percentage points, which is why a single careless mistake can cost a letter grade.

On a 20-question quiz each item is worth 5 points, so there is no such thing as an 88% — you can score 85 or 90 and nothing between. Short tests are therefore far more volatile: one ambiguous question can swing the grade a full letter. Longer tests are statistically fairer for exactly this reason, and it's worth knowing before deciding whether a borderline question is worth querying.

Most courses don't average raw percentages — they weight categories, so a final might count 40% and homework 10%. A 95% on a 10-point quiz barely moves your grade, while the same percentage on the final moves it a lot. To predict a course grade, multiply each category percentage by its weight and add the results; treating all scores as equal is the most common reason predicted grades come out wrong.

Before assuming a grade, check the syllabus for three things: whether the instructor curves, whether the lowest score is dropped, and how rounding works. An 89.5% becomes an A− under standard rounding and stays a B+ where rounding isn't applied — and policies genuinely differ. Where a course drops the lowest quiz, a single bad score may cost nothing at all.