How a raw score turns into a letter
The percentage part is one division. Take the marks you earned, divide by the marks available, multiply by 100. A score of 33 out of 40 gives 82.5 percent. Nothing about that step changes between schools.
The letter is where schools disagree. Most American high schools and colleges publish a plus and minus ladder that starts at 60 for a D- and runs in three point steps to 97 for an A+. Others flatten it to five bands at 90, 80, 70 and 60. A few set the pass line at 50 because their assessments are marked harder. The percentage does not move. The label attached to it does.
That is why the scale selector sits next to the score boxes rather than buried in an advanced panel. Reading 82.5 percent as a B- is only correct if your syllabus draws the B- line at 80.
Counting from wrong answers instead of right ones
Students almost never leave an exam knowing how many they got right. They know how many the teacher marked in red. The default mode takes that number.
- Type the misses. The correct count fills itself in from the question total, so both boxes stay in agreement.
- Type the correct count instead when the marked paper shows a running tally. The wrong box updates the other way.
- Switch to points for tests where questions carry different weights, essays scored on a rubric, or any paper marked out of an odd total like 87.
Half marks belong in points mode. Type 43.5 out of 50 and the percentage picks up the half. The question counter stays on whole numbers because half a question wrong is not a thing most answer keys record.
| Score | Wrong | Percentage | Grade |
|---|---|---|---|
| 27 out of 40 | 13 | 67.5% | D+ |
| 33 out of 40 | 7 | 82.5% | B- |
| 36 out of 40 | 4 | 90% | A- |
| 75 out of 80 | 5 | 93.75% | A |
| 17 out of 20 | 3 | 85% | B |
| 43 out of 50 | 7 | 86% | B |
| 8 out of 10 | 2 | 80% | B- |
| 97 out of 120 | 23 | 80.83% | B- |
Look at the 27 out of 40 row. It passes on a plus and minus scale, sits at a straight D on a five band scale, and clears a comfortable pass at a school that draws the line at 50. One score, three different transcript entries.
Scales differ more than students expect
Plus and minus
Thirteen bands, D- at 60, A+ at 97.
- Standard across most US colleges
- Three point gaps make single answers matter
Five band
A at 90, B at 80, C at 70, D at 60.
- Common in middle school gradebooks
- Wider bands hide near misses
Custom pass mark
Bands stretch between your pass line and 100.
- Set 50 for courses marked on a harder curve
- Set 70 for licensing style tests
The custom setting does not shift only the bottom line. It spreads all thirteen bands across the range you leave above the pass mark, so a pass at 50 puts the A- line near 85 rather than 90. Check the band table after changing it, because the cut offs shown there are the ones the tool grades against.
Rounding, the argument nobody wins
A score of 89.5 percent is either an A- or a B+, and the difference is a school policy rather than arithmetic. Some gradebooks round to the nearest whole percent before comparing against the ladder. Others compare the raw figure and let 89.9 stay a B+.
The rounding checkbox switches between the two. Turn it on and the result line tells you when rounding changed the letter, so you know the grade rests on a policy rather than on the score itself. If your syllabus says nothing about rounding, assume it does not happen. Teachers who round tend to write it down.
Where this calculator stops being right
One test with equally weighted questions is a narrow problem, and this page solves that problem only. Several common grading setups fall outside it.
- Weighted categories. If homework counts 20 percent and exams 50 percent, the course grade needs a weighted average across categories. This tool grades the single paper in front of you.
- Curves. A curve set to the class mean or top score ignores fixed percentage bands entirely. No fixed ladder predicts a curved result.
- Rubric marking. Essays scored on four criteria out of five points each convert to a percentage, but teachers often map rubric totals straight to letters with their own table.
- Dropped scores. Courses that drop the lowest quiz change what the paper is worth after the fact, sometimes to nothing.
- Negative marking. Entrance exams that subtract for wrong answers need the penalty applied before any percentage makes sense. Counting misses here overstates the score.
- Non US systems. UK classifications, Indian division marks, German 1 to 5 grades and the IB 1 to 7 scale do not map onto letter bands cleanly. Convert with your institution's own table.
For the neighbouring jobs, other pages fit better. Combining several test scores into a course grade belongs to the grade calculator, semester and cumulative averages to the GPA calculator, and plain averaging of a list of marks to the average calculator.
