Assignment Grade Calculator
This assignment grade calculator turns points earned and points possible into a percent score, a standard letter grade, and the points you lost along the way. It is built for the everyday homework, lab, or project check — "I got 17 out of 20, what is that?" — with the deduction breakdown students need to see exactly where the grade slipped.
Points you scored on the assignment.
Total points the assignment was worth.
Assignment score — B
85%
- Percentage score
- 85%
- Points lostPoints left on the table on this assignment.
- 3
- Points earned
- 17
How it was calculated
- Score: 17 ÷ 20 × 100 = 85.0% (B).
- Points lost: 20 − 17 = 3.
How it works
The percent score is (points earned ÷ points possible) × 100. Points lost is simply points possible minus points earned.
Unlike question-count scoring, this works for any point scheme — a 20-point lab, a 100-point essay, or a 13-point homework set all use the same math.
The letter grade follows the standard US scale: A for 90% and up, B for 80–89%, C for 70–79%, D for 60–69%, F below 60%.
Worked examples
17 out of 20 on a lab report
17 ÷ 20 × 100 = 85%, a B, with 3 points lost. Each point on this assignment was worth 5 percent, so the lost 3 points cost 15 percent.
45 out of 50 on an essay
45 ÷ 50 × 100 = 90%, an A, with 5 points lost. The essay’s 50-point scale means every 5 lost points drop the grade by a full 10 percent.
How to measure
- Enter the points exactly as marked on the rubric — including half points like 8.5 — rather than rounding first.
- Check whether the "points possible" includes extra credit; if it does, scores above 100% are legitimate.
- For multi-part assignments, add up all earned points and all possible points before entering — do not average the parts.
- If the teacher dropped the lowest assignment, remove it from your records entirely instead of entering a zero.
Assumptions & limitations
Planning estimate
- All points within the assignment are treated equally; a rubric that weights sections differently needs a weighted calculation.
- The standard US letter scale is applied (A 90+, B 80+, C 70+, D 60+, F below 60); your course may use different cutoffs.
- Partial credit must already be reflected in the points earned you enter — the calculator does not split individual questions.
- No curve is applied; the percent and letter are raw.
Frequently asked questions
Divide your points by the total points and multiply by 100. Scoring 17 out of 20 is 17 ÷ 20 × 100 = 85%, a B. This calculator also shows how many points you lost, which is the fastest way to see where the grade went.
It is the gap between a perfect score and yours — 3 points on a 20-point assignment. Combined with the per-point value (100 ÷ points possible), it tells you exactly how expensive each mistake was.
Yes — the inputs accept decimals, so 8.5 out of 10 works fine and gives 85%. Enter the precise marked score rather than rounding, since rounding before the math introduces small errors.
The math is the same, but the framing differs: this tool thinks in rubric points (17/20 on a lab) while the test tool thinks in question counts (42/50 on an exam). Use whichever matches how your work was marked.
Enter the base points possible and your total including the bonus — a score like 22 out of 20 gives 110% and is reported as-is with an A. Do not inflate "points possible" with the bonus or the percent will understate your work.