Calculate your weighted course grade as the sum of each score multiplied by its weight, divided by the total of all the weights (grade = sum(score × weight) ÷ sum(weight)) — a single percentage that represents every graded item on your syllabus. The weighting matters because a 5% quiz should not count the same as a 40% final exam; treating them equally gives a misleading number. The Grade Calculator runs that formula as you type scores and weights, then pairs your weighted percentage with a letter grade on the standard US scale. Everything happens locally in your browser, so nothing is uploaded, and the percentage plus letter grade update instantly as you add, change, or remove a row. That single weighted-average formula is the engine behind every grade report; the rest of this guide walks through reading your syllabus, the exact steps to enter your scores, why a plain average misleads, how letter-grade cutoffs vary by school, and how to reuse the same calculator to plan your final exam score.
What a Weighted Grade Calculator Does
A weighted grade calculator turns a stack of assignment scores into the single number that lands on your report card. Each score is paired with a weight — how much that item is worth toward your overall grade — and the tool combines them with the formula grade = sum(score × weight) / sum(weight). The result is your weighted average, which it converts to a letter grade using the standard US scale. Plain averages treat a 5% quiz the same as a 40% final exam, which is misleading; weighting fixes that by giving each item its true share of the total. Because the math runs locally in your browser, nothing about your scores is uploaded, and the percentage plus letter grade update instantly as you type.
Read Your Syllabus First to Find Each Weight
Before you start entering numbers, pull up your course syllabus and locate the grading breakdown. Most syllabi list categories — homework, lab essays, midterm, final exam — with a percentage weight beside each one. Some syllabi list weights by point count instead, in which case you convert points into percentages by dividing each category's points by the total points and multiplying by 100. Write the weights down the way they appear on the syllabus, even if they do not reach 100, because the calculator normalizes for you. If the syllabus includes extra-credit items, enter them as their own row with the bonus number as the score — values above 100 are accepted and simply raise your weighted average. If the syllabus changes mid-term, update your weights and rerun the calculator so your standing stays accurate.
Calculate Your Grade Step by Step
- List each item you already have a score for — homework, quiz, essay, lab report, midterm — and write the score as a percentage out of 100.
- Find the weight for each item on your syllabus.
- Open the Grade Calculator and add a row for each item by typing the score and weight into the two number fields. The name field is optional and is just there to help you keep track of which row is which.
- Use the Add row button for additional items, or the remove button next to a row if you entered one by mistake.
- Read your weighted grade and letter grade instantly below the rows — there is no submit step and nothing to refresh, the result updates as you type.
- If your weights do not add up to 100, do not worry. The calculator normalizes automatically by dividing by the actual total weight, so weights of 20, 20, and 10 (summing to 50) still produce a correct weighted average; the total weight is shown so you can spot a missing category.
Plain Average vs Weighted Average
A plain (unweighted) average adds the scores and divides by the number of items, treating every quiz, essay, and exam as if it counted the same. A weighted average instead multiplies each score by how much that item is worth toward the final grade, then divides by the total weight. The difference can be large. Take a simple two-item class: a 90% on work worth 50% and an 80% on work worth 50% give (90 × 50 + 80 × 50) / 100 = 85, a B on the standard scale. Now move the same two scores into a class where the lower-scoring item is worth 70% — say a 70%-weighted final and a 30%-weighted project — and the result becomes (80 × 70 + 90 × 30) / 100 = 83, a B still but lower, because the lower score now carries more of the grade. Treating the final as equal to the project would have given 85 either way, hiding the real risk.
Letter Grade Cutoffs and Scale Variations
The Grade Calculator labels your result using the most common US letter-grade scale.
| Percentage | Letter Grade |
|---|---|
| 90 and above | A |
| 80 to 89 | B |
| 70 to 79 | C |
| 60 to 69 | D |
| Below 60 | F |
This default matches most American high schools and colleges, but the cutoffs vary. Some schools start A at 93, some draw the line between B and C at 73, some grade on a plus-minus scale (A−, B+, B, B−, and so on) with their own bands, and some systems outside the US pass at 50. A few schools also count an A as 4.0 GPA while an A− is 3.7 — see our weighted grade formula and cutoffs guide for the wider table. Always check your own syllabus before treating a letter as final, especially if your course grade is right on the boundary.
Plan Your Final Exam With the Same Calculator
Once your graded rows are in, you can reuse the same tool to forecast the final. Add the final exam as a new row, give it the weight from your syllabus (often 20%, 30%, or 40%), and try different scores in that row while watching the overall percentage update. When the number reaches the letter grade you want, that score is the mark you need on the final. This "what-if" approach is the most reliable way to set a target because it uses your real weights instead of guessing. For a deeper walk-through of the same workflow, see our guide on planning your final grade with weights. Pair the result with a study planner if you want to break the preparation into sessions.
Common Mistakes That Throw Off the Math
Three slips cause most miscalculations. First, entering 0.90 when you mean 90, which is a far smaller number than the 90 you intended; always type your score as a percentage out of 100. Second, mixing points and percentages inside the same list — a 45/50 quiz (90%) and a 180/200 essay (90%) are fine to combine, while a 45/50 quiz mixed with a raw "85" essay is not. Third, copying weights from a friend whose syllabus is different — instructors vary, and a 5-point difference in final-exam weight can change the score you need to pass. Also remember that weights must be zero or positive numbers; a negative weight would flip the sign of your grade.