Grade calculator
Two calculators in one: a weighted average across all your assessments with a letter-grade readout, and a final-exam calculator that solves for the score you need to hit a target overall grade. Everything runs in your browser as you type.
Weighted grade calculator
Enter each assessment's name, your score, and its weight toward the final grade. Add or remove rows freely — the average recalculates as you type.
| Assessment | Score % | Weight % | Remove |
|---|
Final grade calculator — what do I need on the final?
Enter your grade going into the final, how much the final is worth, and the overall grade you're aiming for.
How weighted grades work
Most courses don't weigh every assignment equally — a final exam usually counts for more than a single homework set. A weighted average accounts for that by multiplying each score by its own weight before dividing by the total weight, instead of just averaging the raw percentages:
overall = (score₁ × weight₁ + score₂ × weight₂ + …) / (weight₁ + weight₂ + …)
If every weight is already a percentage and they sum to 100, that simplifies to dividing the weighted sum by 100. If they don't sum to 100 — because you haven't entered every assessment yet, or a syllabus weights things in raw points rather than percentages — the calculator still divides by whatever weight you've actually entered. That's the normalization gotcha below.
Worked example
Homework is worth 40% of the grade and you scored 90%. The midterm is worth 60% and you scored 80%:
(90 × 40 + 80 × 60) / (40 + 60) = (3600 + 4800) / 100 = 8400 / 100 = 84%
84% maps to a B on the standard scale below.
The final-grade formula, derived step by step
The question "what do I need on the final?" is just the weighted-average formula solved backwards. Let current be your grade going into the final, w be the final's weight as a fraction of the whole grade (20% becomes 0.2), desired be the overall grade you want, and required be the unknown score on the final. Everything except the final already contributes current at a combined weight of (1 − w), and the final contributes required at weight w:
desired = current × (1 − w) + required × w
Solve for required by moving the known term to the other side and dividing by w:
desired − current × (1 − w) = required × w required = (desired − current × (1 − w)) / w
That's the exact formula the calculator above runs on every keystroke.
Three worked examples
Achievable. Current grade 88%, final worth 20%, target 90%:
required = (90 − 88 × 0.8) / 0.2 = (90 − 70.4) / 0.2 = 98%
Already secured. Current grade 95%, final worth only 10%, target 80%:
required = (80 − 95 × 0.9) / 0.1 = (80 − 85.5) / 0.1 = −55%
A negative required score means the target is already locked in — the final can't pull the overall grade below 80% even at 0%.
Not achievable. Current grade 70%, final worth only 10%, target 90%:
required = (90 − 70 × 0.9) / 0.1 = (90 − 63) / 0.1 = 270%
270% is impossible on any exam, so the target grade cannot be reached through the final alone — the weighting is too small relative to how far behind the current grade is.
The "weights must sum to 100" gotcha
If you enter three assessments worth 20%, 20% and 20% (60% total) because that's all that's been graded so far, the calculator does not treat the missing 40% as zero. It divides the weighted sum by 60, not by 100 — giving you the grade of the work that's actually been completed. This matters because dividing by 100 anyway would silently understate your grade by exactly the fraction that's ungraded.
The tool labels this explicitly: once your weights reach 100% (within rounding), the note switches from "grade of completed work" to your plain overall grade. If your syllabus weights by raw points instead of percentages (say, 150 points for a final out of 1,000 total), convert to percentages first — divide each component's points by the course total and multiply by 100 — or the weights entered here won't correspond to your syllabus's actual scheme.
The standard grade scale
This is the letter mapping the calculator above uses — the common US 10-point scale. It varies by school and even by instructor: some add an A+, some draw the B+/B line at a different percentage, some round a borderline score up. Check your own syllabus for the scale that actually governs your grade.
| Letter | Minimum % |
|---|---|
| A | 93 |
| A− | 90 |
| B+ | 87 |
| B | 83 |
| B− | 80 |
| C+ | 77 |
| C | 73 |
| C− | 70 |
| D+ | 67 |
| D | 63 |
| D− | 60 |
| F | below 60 |
Rounding, borderlines, and being honest about precision
The calculator keeps full precision internally and only rounds for display, to two decimal places. A weighted average of 89.996% displays as 90.00% and is reported as an A−, because it is one — but if your instructor rounds differently (say, truncating instead of rounding, or rounding at one decimal place instead of two), your official grade could land a fraction of a point on the other side of a letter boundary. Borderline percentages are exactly where "what the calculator says" and "what your transcript says" are most likely to diverge, and that gap is a rounding-convention difference, not a bug in either one.
The final-grade calculator has the same honesty built in for its two edge cases: a required score reported as, say, 100.4% is not "basically 100" — it is mathematically over the line, and the tool says so rather than rounding it into looking achievable.
Use cases & limitations
Where this is useful
- Planning before a final. Know exactly what score locks in the grade you want, instead of guessing.
- Checking a syllabus's weighting. Enter the components as your instructor describes them and see whether the numbers add up to a sensible overall grade.
- Mid-semester what-ifs. Swap in a hypothetical score on an upcoming assignment to see how much it could move your overall grade.
What it cannot do
- It doesn't know your school's rounding or curve policy. Every institution — and often every instructor — handles borderline percentages, curves, and extra credit differently. This tool applies none of that; it does the arithmetic you give it.
- It assumes simple linear weighting. "Best 8 of 10 quizzes," capped extra credit, or a weight that changes partway through the term all need you to pre-compute the numbers you enter, or aren't representable here at all.
- The letter scale is a US convention, not a standard. Outside (and even within) the US, scales vary enough that the letters here may not match your institution's grading rubric at all.
- It is not your official grade. Treat every number here as a planning estimate, and confirm anything that matters against your instructor's own gradebook.
Frequently asked questions
What happens if my weights don't add up to 100%?
The calculator still gives you an answer: it normalizes over whatever weight you've entered so far and labels the result as the grade of completed work, rather than a final overall grade. If you've only entered assessments worth 60% of the course, the average is computed over that 60% — not against the missing 40% as if it were zero. Once every assessment has a weight and the total reaches 100%, the label switches to your overall grade automatically.
How is the letter grade worked out?
Against the standard US 10-point scale shown below the calculator: 93 and above is an A, 90–92.99 is A−, and so on down to F below 60. This is the most common convention, but it is not universal — check your own syllabus, since some schools add an A+, some round a borderline percentage up, and some use a different point scale entirely. Treat the letter here as a reference, not your school's authority.
What does it mean if the required final score is over 100%?
It means the grade you want is not mathematically reachable with the weighting you entered — no score on the final, not even a perfect one, gets you there. That usually means the current grade needs to improve through some other route (extra credit, a resubmission, a grade recalculation) or the target grade needs to be adjusted.
What does it mean if the required score is zero or negative?
Your current grade already guarantees the desired outcome or better, regardless of what you score on the final — the arithmetic comes out at or below 0%. Most courses still require some minimum final-exam performance or attendance to pass at all, so "secured" describes the maths, not your school's specific policy on skipping a final.
Does this account for extra credit, dropped scores, or curves?
No — this is a straightforward weighted-average calculator. Extra credit, dropping your lowest score, or a curve applied afterwards all change the numbers you'd enter, or need a second pass through the calculator, and every school implements them differently. Enter the scores and weights your own syllabus specifies.
Does every school grade on this exact scale?
No. This is the common US convention, but plus/minus boundaries, whether an A+ exists, and how a borderline percentage rounds all vary by institution and even by individual instructor. Always check your syllabus for the scale that actually applies to your grade.
Is anything I type sent anywhere?
No — every calculation runs in your browser. What you type into either calculator never leaves your device; there's no account, no server round-trip, and nothing is saved between visits. Refreshing the page resets both calculators to their example values.