Weighted Grade Average Calculator

Subject weighted average: formula and example

In a weighted average by subject, each course's credit load becomes its weight: MP = Σ(gradeᵢ · creditᵢ) / Σ creditᵢ. A subject worth more credits or hours pulls harder on the final number. Take this example: Portuguese 5 credits × grade 8, Math 5 × 7, PE 2 × 9, which works out to (40 + 35 + 18) / 12 = 93/12 = 7.75. A plain arithmetic mean would hand the same student 8.0. The weighted figure is lower because PE, even with a high grade, carries less academic weight than the core subjects.

Applications

K-12 grading: under Brazil's LDB (Law 9.394/1996), a school is free to weight subjects differently on the report card. Vestibular exams set weights per area according to the chosen major. Engineering programs usually give Math and Physics a 3× weight, while medical schools lean on Biology and Chemistry. ENEM: the raw score runs on Item Response Theory (TRI), but universities applying via SiSU still set their own per-area weights when they rank candidates.

FAQ

What weights should I use? Go with the credit hours or weekly class hours set out in the curriculum. When a school publishes no weights at all, fall back on the plain arithmetic mean.

Can I include a failed subject? Yes. Count every subject in the period. A low grade attached to a high weight will drag the average down hard.

Does the formula change if grades are on a 0–100 scale? No. It is scale-invariant. Only the resulting average lands on a different scale.