Weighted Grade Calculator: Class Average & Score Needed

Weighted Grade Calculator

A weighted grade calculator works out a class grade when some assignments count more than others. Each graded category, such as homework or a midterm exam, has a score and a weight. The weight is the share of the final grade that the category is worth. The calculator combines the scores into one weighted average and, if a target grade is set, shows the score needed on the remaining work to reach it.

What the calculator does

Each row holds one graded category: an optional name, a score from 0% to 150%, and a weight from 0% to 100%. Scores above 100% represent extra credit inside a category. The calculator accepts up to 20 categories, and the weights together may not add up to more than 100%.

From the rows that have both a score and a weight, the calculator reports three numbers:

• Current weighted average: the grade earned so far, counting only graded work.
• Weight graded: how much of the course the entered categories cover.
• Weight remaining: the rest of the course, calculated as 100% minus the weight graded.

An optional target grade (0% to 150%) adds a fourth number: the average score needed on the remaining weight to finish the course at that target.

The weighted grade formula

The calculator uses the weighted arithmetic mean, a standard method described in the Wikipedia article "Weighted arithmetic mean". Each score is multiplied by its weight, the products are added, and the sum is divided by the total weight:

A = (s₁ × w₁ + s₂ × w₂ + … + sₙ × wₙ) / (w₁ + w₂ + … + wₙ)

• A is the current weighted average.
• sᵢ is the score in category i, as a percentage.
• wᵢ is the weight of category i, as a percentage of the course grade.

A simple average would treat every category the same. The weighted average lets a 50% exam count five times as much as a 10% homework category.

The score needed on remaining work

The final course grade is the graded part plus the ungraded part, each scaled by its weight. Solving that relationship for the unknown score gives:

x = (100 × G − Σ(sᵢ × wᵢ)) / r

• x is the average score needed on the remaining work.
• G is the target grade.
• Σ(sᵢ × wᵢ) is the sum of score × weight over the graded categories, which is the number of grade points already earned out of 100.
• r is the remaining weight, 100 minus the sum of the graded weights.

The result is rounded to two decimal places and then judged:

• Above 100%: the target is out of reach without extra credit on the remaining work.
• 0% or below: the target is already secured. Any score on the remaining work finishes at or above it.
• Otherwise: the target is attainable, and the calculator shows the required score.

Worked example

A student has three graded categories in a course:

The weighted sum is 92 × 20 + 88 × 15 + 78 × 25 = 1,840 + 1,320 + 1,950 = 5,110. The graded weight is 20 + 15 + 25 = 60%. The current weighted average is 5,110 ÷ 60 = 85.17%. The remaining weight is 100 − 60 = 40%.

To finish at a target of 90%, the required score on the remaining 40% is:

x = (100 × 90 − 5,110) / 40 = 3,890 / 40 = 97.25%

The student needs an average of 97.25% on the rest of the course. A target of 95% would need 109.75%, which is more than 100%, so that target is out of reach without extra credit.

Conventions this calculator uses

A few choices could reasonably be made differently, so they are stated here.

• Incomplete rows are ignored. A row missing its score or its weight does not count toward the average or the graded weight. The calculator measures the grade on work already graded. Some other calculators instead treat missing scores as zero, which answers a different question.
• Ungraded weight is derived, not entered. The remaining weight is always 100% minus the graded weights, so the two parts always cover exactly the whole course. Weights that total more than 100% are rejected with an error rather than rescaled.
• Extra credit is allowed but bounded. Scores and targets may go up to 150%, since many courses award extra credit within a category. "Out of reach" therefore means the required score exceeds 100%, the most a student can earn without extra credit on the remaining work.
• The verdict matches the displayed number. Feasibility is judged on the required score after rounding to the two decimal places shown, so the message and the number on screen never disagree.
• Decimal weights are compared safely. Weight totals are snapped to six decimal places before being compared with 100%. Without this, weights such as 16.1 + 48.2 + 35.7 would be misread by tiny binary floating-point errors as slightly over or under 100%.

Frequently asked questions

What is a weighted grade?

A weighted grade is a course average in which each category counts in proportion to its weight. If exams are worth 50% of the grade and homework 20%, an exam score moves the final grade two and a half times as much as an equal homework score.

What if the weights do not add up to 100%?

That is normal partway through a course. The calculator averages only the graded categories and reports the leftover share as weight remaining. Weights that add up to more than 100% are an input error and are rejected.

Can a score be higher than 100%?

Yes. Scores up to 150% are accepted to allow for extra credit within a category. The target grade has the same upper bound.

What does the required score mean?

It is the average the student must earn across all remaining work to end the course at the target grade. If several assignments remain, their combined weighted average must reach that number, not each one individually.

When is a target grade out of reach?

When the required score on the remaining work is above 100%. At that point no combination of normal scores can lift the average enough, and only extra credit could close the gap.

How is this different from a simple average?

A simple average adds the scores and divides by the number of categories, so every category counts equally. A weighted average multiplies each score by its weight first, which matches how most syllabi define the final grade.