Test Grade Calculator
Turn a raw test score into a percentage and letter grade, and see how many more marks a target grade would have needed.
How to use this calculator
- 1Choose whether you know how many you got right, how many you got wrong, or a points total.
- 2Enter the score and the total available.
- 3Set a target grade to see how many more marks it would have taken, and check the boundary table for where each letter starts on this particular test.
How the calculation works
Percentage = (marks earned ÷ marks possible) × 100- marks earned
- Questions answered correctly, or points scored
- marks possible
- Total questions, or total points available
The letter grade comes from a lookup against a grading scale, not from a formula — which is exactly why scales differ between institutions and the letter shown here is only as right as the scale you selected.
The plus/minus scale used here is the common US convention: 93 and above is an A, 90–92.99 an A−, 87–89.99 a B+, and so on in 3-and-4-point steps. The simple scale collapses each letter into a single 10-point band.
Worked example
34 correct out of 40 questions
- 1.Percentage: (34 ÷ 40) × 100 = 85%.
- 2.On the plus/minus scale, 85% falls in the 83–86.99 band, which is a B.
- 3.Each question is worth 100 ÷ 40 = 2.5% of the total.
- 4.A 90% target needs 0.90 × 40 = 36 questions, so the score was 2 questions short of an A−.
Result: 85% — a B, two questions short of 90%
From raw score to percentage
The arithmetic behind a test grade is the simplest part: divide what you scored by what was available and multiply by a hundred. What varies — and what actually determines the letter on the transcript — is everything layered on top of that percentage: which scale the institution uses, whether the marks are weighted, and whether the distribution is adjusted after the fact.
One figure worth noticing on any test is how much a single question is worth. On a 40-question test each question moves the grade by 2.5 percentage points, which means two questions can cross a letter boundary. On a 200-question exam each one is worth 0.5 points and individual questions barely matter. That ratio is why short quizzes feel so much higher-stakes per question than long exams.
Why grading scales differ
There is no universal mapping from percentage to letter, and the differences are larger than most people assume.
- The 10-point scale — the most common US convention — 90+ is an A, 80s a B, 70s a C, 60s a D. Simple, and the default assumption in most American schools.
- Plus/minus refinement — subdivides each letter, typically putting A− at 90–92, A at 93–96 and A+ at 97+. Whether an A+ exists at all, and whether it is worth more than 4.0 in GPA terms, varies by institution.
- The 7-point scale — used by some schools and historically common in parts of the US, where an A starts at 93 rather than 90 — the same raw score can be a full letter lower than on a 10-point scale.
- Percentage-only systems — much of the world outside the US reports percentages or a numeric grade directly with no letter conversion at all, and passing thresholds differ sharply between countries.
Curving, and what it actually means
A "curve" is not one thing. In its strictest statistical sense it means fitting grades to a normal distribution, with a fixed proportion of each letter awarded regardless of raw scores — so a class where everyone does well still produces the same number of Cs. In everyday use it much more often means something looser: adding a flat number of points to everyone, scaling so the top score becomes 100%, or dropping the worst-performing question.
The distinction matters because the two have opposite implications. A true normal curve is competitive — your grade depends on how everyone else did, so helping a classmate can hurt you. A flat adjustment is not competitive at all. If a syllabus says "curved", it is worth finding out which is meant.
What this calculator cannot tell you
This converts one test into one grade. A course grade is almost always a weighted combination — homework, quizzes, a midterm, a final, participation — each carrying a different share of the total. A 70% on a quiz worth 5% of the course barely registers; the same 70% on a final worth 40% moves the course grade substantially. For that question, the calculation you want is a weighted average across all components, which is what a final grade calculator handles.
What this assumes, and where it stops
Assumptions
- Every question is worth the same number of marks. Tests with differently weighted sections need the points mode, using the actual point totals.
- The grading scale selected matches your institution's. The plus/minus boundaries used here are the common US convention, not a universal standard.
- No curve, scaling or dropped questions have been applied to the raw score.
Limitations
- Handles one test in isolation. It does not compute a course grade from several weighted components — use the Final Grade Calculator for that.
- Negative marking (losing marks for wrong answers, as in some standardised exams) is not modelled; enter the net points total instead.
- The GPA points shown are the common US 4.0 mapping. Many institutions differ, particularly on whether A+ exceeds 4.0 and how they treat D grades.
Common questions
What grade is 34 out of 40?
85%, which is a B on the standard 10-point scale (and still a B with plus/minus grading, since the B band runs 83–86.99). Reaching 90% for an A− would have needed 36 correct — two more questions.
Why does my school say 93% is an A when other scales say 90%?
Both conventions are in use. The 10-point scale starts an A at 90; the older 7-point scale starts it at 93, with each letter spanning 7 points instead of 10. Some institutions also use 90 for a plain A but 93 for an A on a plus/minus scale. The scale is set by the institution, so the syllabus is the authority.
How is this different from a final grade calculator?
This one converts a single completed test into a percentage and letter. A final grade calculator answers a forward-looking question: given your current grade and how much the final exam is weighted, what do you need to score on it to reach a target course grade.
Formula and content last reviewed on .
Results are estimates for information only, not professional advice.
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