Test Grade Calculator
Convert a test score to a percentage, letter grade, and grade points, with an optional curve and a table showing the grade for every number of mistakes.
How to use this calculator
- 1Enter how many questions were answered correctly and how many there were in total.
- 2Add a curve in percentage points if your teacher applied one.
- 3Set the pass mark if it is not the default 60%.
- 4Use the table to see how each additional mistake would change the grade.
How it works
Test score to grade
percentage = (correct ÷ total) × 100 + curve A: 90–100 B: 80–89 C: 70–79 D: 60–69 F: below 60 plus/minus: the top and bottom 3 points of each band percentage per question = 100 ÷ total questions
The score itself is a simple ratio. What matters more in practice is the value of a single question: on a 50-question test each answer is worth 2 percentage points, but on a 20-question test each is worth 5 — enough to move a grade by a full letter. That is why short tests produce far noisier grades than long ones, and why one careless mistake hurts so much more on a quiz than on a final.
Worked example
Scoring 43 out of 50 gives 43 ÷ 50 × 100 = 86%, a B. One more correct answer would give 88% and a B+; the seven wrong answers cost 14 percentage points because each question is worth 2.
Test Grade Calculator: the complete guide
Why short tests produce unfair grades
On a 20-question test, every question is worth 5 percentage points. Missing two drops you from 100% to 90% — from an A+ to an A−. On a 100-question test, missing two costs 2 points and changes nothing.
This is measurement error, not knowledge. A student who genuinely knows 85% of the material will score anywhere from roughly 75% to 95% on a 20-question test simply depending on which questions were asked, and that spread narrows as the test lengthens.
It is the strongest argument for grading on many small assessments rather than one or two large ones: the errors average out, and the final grade reflects knowledge rather than luck of the draw.
What a curve actually does
The word covers several different practices. A flat curve adds the same number of points to everyone, which is what this calculator models. It is the simplest and the fairest to individual students, because nobody's grade depends on how their classmates performed.
Scaling to the top score sets the highest mark to 100% and shifts everyone by the same amount. A true bell curve is different again: it forces a fixed distribution of letter grades regardless of absolute performance, which means students compete against each other rather than against the material. That approach is now widely criticised for exactly that reason.
Some instructors instead drop the worst-performing question — usually a sign the question was badly written rather than that the students were unprepared. Item analysis, where a question that top scorers get wrong is flagged as defective, is the formal version of this.
Percentage, letter, and GPA
Three scales describe the same performance, and each loses information from the one before. A percentage is continuous. A letter grade bins it — 90 and 93 are both an A− or an A depending on the scale. Grade points compress further, and on many scales an A and an A+ both count as 4.0, so the difference disappears entirely.
The banding is not standardised. A 7-point scale puts an A at 93 and above; a 10-point scale puts it at 90. Some institutions cap the GPA at 4.0 while others award 4.3 for an A+. Weighted GPAs add a point for honours and AP courses, which is how a GPA above 4.0 appears on a transcript.
Because of this variation, a raw percentage is the only figure that transfers reliably between systems. Always check the syllabus before assuming a band.
Rounding at the boundary
An 89.5% sits exactly on the line between B+ and A−, and whether it rounds up is a policy question rather than a mathematical one. Most institutions round to the nearest whole percent, which makes 89.5 an A−, but a significant number truncate instead, which makes it a B+.
This is worth knowing before the final exam rather than after. If you are at 89.4% going into an assessment worth 20% of the grade, the calculator's "extra correct answers needed" line tells you precisely what it takes to clear the boundary rather than land on it.
Frequently asked questions
What letter grade is 43 out of 50?
86%, which is a B on the standard scale. Two more correct answers would give 90% and an A−. The table above shows the grade for every nearby number of mistakes.
How do I calculate a test percentage?
Divide the number correct by the total and multiply by 100. For partial credit, add up the points earned and divide by the points available — the calculator accepts half-marks in both fields for exactly this case.
What does curving a grade mean?
Adjusting scores upward after the fact, usually because the test was harder than intended. A flat curve adds the same points to everyone and is the fairest version. A true bell curve forces a fixed distribution of letters, which makes students compete against each other and is increasingly avoided.
Is 90% an A or an A−?
It depends on the scale. On a 10-point scale with plus/minus, 90–92 is an A− and 93 and above is an A. On a scale without plus/minus, anything from 90 is simply an A. Check the syllabus, since the difference is a third of a grade point.