The weighted grade formula
How to calculate a weighted grade: multiply each score by its weight, add all of those products together, and divide by the total weight. That is the whole method, and it gives a weighted average grade, not a simple average.
Weighted grade = (score × weight + score × weight + …) ÷ total weight
For example, with Homework 85% at 20%, Quizzes 90% at 15%, a Midterm of 78% at 25%, and a Project of 92% at 10%, the weighted grade is 84.57%. The steps below show exactly how that number is reached, and why it is not the same as adding the four scores and dividing by four.
Worked example, step by step
This is the same sample used in the Average Grade Calculator on this site, so you can check every step against the tool.
| Assignment | Score | Weight |
|---|---|---|
| Homework | 85% | 20% |
| Quizzes | 90% | 15% |
| Midterm | 78% | 25% |
| Project | 92% | 10% |
Step 1 — Multiply each score by its weight. 85 × 20 = 1,700; 90 × 15 = 1,350; 78 × 25 = 1,950; 92 × 10 = 920.
Step 2 — Add the products. 1,700 + 1,350 + 1,950 + 920 = 5,920.
Step 3 — Divide by the total weight entered. The weights so far add to 20 + 15 + 25 + 10 = 70, so 5,920 ÷ 70 = 84.57%.
That division by 70, rather than by 100, is the key point. If only part of a course has been graded, the weighted grade so far is still correct on the work entered — it is not 59.20%, which is what you would get if you divided 5,920 by 100 before the remaining 30% exists.
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Weighted vs unweighted: why the answers differ
The simple, unweighted average of the same four scores is (85 + 90 + 78 + 92) ÷ 4 = 86.25%. That is higher than the weighted 84.57%, and the reason is specific, not a rounding difference: the lowest score, the 78% Midterm, also carries the heaviest weight at 25%. A simple average treats every score equally, so it understates how much that midterm pulls the grade down. A weighted grade does the opposite — it gives each score exactly the influence your syllabus gives it.
Use a simple average only when every assignment genuinely counts equally. Use a weighted grade whenever a syllabus lists different weights, even if some weights look small. A 10% project will not rescue a 25% midterm, and a weighted calculation shows that honestly instead of hiding it.
This is also why the phrase “average grade calculator without weight” means something different: without weights, the tool is just averaging scores equally. That is a valid calculation, but it is not a weighted grade, and it should not be used to report a course grade that has weights.
What if the weights do not add up to 100%?
Three cases come up, and they need different handling.
Weights add to less than 100% because work is still to come. This is normal mid-course. Divide by the weight entered so far, as in the example above, and read the result as “my weighted grade so far.” Do not divide by 100 yet, and do not treat ungraded work as zero.
Weights add to less than 100% at the end of the course. Check the syllabus first. A missing weight usually means a row was left out, or a category such as participation was forgotten. Add the missing row before trusting the result.
Weights add to more than 100%. Something is entered twice, or a weight was typed as a score. Re-check each row against the syllabus, because a total above 100% will quietly shrink every score’s real influence.
If you want to know what you still need, rather than what you have so far, that is a different calculation. Put your current weighted grade into the Final Grade Calculator with your target grade and the final exam weight, and it will show the score needed on the final.
Weighted grades with points and letters
A grade calculator with points and weight works the same way, with one extra step first: convert each row to a percentage before you weight it. A row of 17 out of 20 is 17 ÷ 20 × 100 = 85%, and then 85% is multiplied by that row’s weight exactly as above. Never multiply raw points by a percentage weight — a 17-point row and a 90-point row do not have the same scale, and mixing them is the most common source of a wrong weighted grade.
Letter grades need the same conversion. Convert each letter to the percentage your school uses for it, or use the Letters mode in the Average Grade Calculator, and then apply the weights to those percentages. Do not average letter grades as if A, B and C were equally spaced numbers — the percentage behind each letter is what carries the weight.
What happens if you drop your lowest grade?
Dropping a grade in a weighted course does not just remove a score. It also removes that score’s weight from the total, so the remaining weights are divided by a smaller total. In the example above, dropping the 78% Midterm would remove both the 78 and its 25% weight, leaving (1,700 + 1,350 + 920) ÷ (20 + 15 + 10) = 3,970 ÷ 45 = 88.22%. That is a large jump, which is why a drop-lowest rule should only be used when your syllabus actually allows it, and why the Average Grade Calculator names the grade it drops, so you can see the effect instead of guessing at it.
Common mistakes when you calculate a grade average
- Adding scores and dividing by the number of assignments. That is the unweighted average, not a weighted grade, and in the example it overstates the result by 1.68 percentage points (86.25% instead of 84.57%).
- Mixing points and percentages in one row. Convert points to a percentage first, then weight it.
- Forgetting a weight, or entering one twice. Check that every row has a weight and that the total matches your syllabus. The Average tool shows “Weighted by ___% entered so far” so a missing row is visible.
- Counting ungraded work as zero. Future work is not a zero yet. Leave it out until it is graded, and divide by the weight entered so far.
- Rounding at every step. Keep full numbers through the multiply and add steps, and round only the final result, to 84.57% in this example. Early rounding is how small errors become a full point.
Try it with your own grades
Put your own scores and weights into the Average Grade Calculator. It uses this same formula, in Percentage, Letters, or Points mode, with an optional drop-lowest, and it shows the stacked weight bar so you can see which assignment is actually moving your grade most. If you then want to work backwards from a target, use the Final Grade Calculator to find what you need on the final exam.
Frequently asked questions
Do weights have to add up to 100% to calculate a weighted grade?
No. Divide by the total weight entered so far. Weights add to 100% only when the whole course has been graded. Mid-course, dividing by the weight so far gives your weighted grade so far; dividing by 100 would understate it.
How do I calculate a weighted grade with letter grades or points?
Convert each row to a percentage first — points earned divided by points possible, times 100, or the percentage your school assigns to each letter — and then multiply that percentage by its weight. Weight the percentages, never raw points or letters on their own.
What is the difference between a weighted grade and a simple average?
A simple average gives every score equal influence. A weighted grade gives each score the influence its syllabus weight gives it. In the example in this article, the simple average is 86.25% and the weighted grade is 84.57%, because the lowest score also had the highest weight.
What if a grade has no weight?
Then it is not part of a weighted calculation. Either find its weight in your syllabus and add it, or calculate an average grade calculator without weight — a simple average — and label it as such. Do not silently treat a no-weight grade as if it counted equally in a weighted course.