How to calculate grades with percentages
Calculate test percentages and weighted final grades with clear formulas and examples.
Percentage score on a test
Divide the points earned by the points available, then multiply by 100:
percentage score = points earned / total points x 100Scoring 42 out of 50 gives 42 / 50 x 100 = 84%.
Weighted final grade
When assignments have different weights, multiply every grade by its decimal weight and add the results:
final grade = grade 1 x weight 1 + grade 2 x weight 2 + ...Suppose exams count for 60%, homework for 25% and a project for 15%:
85 x 0.60 + 92 x 0.25 + 80 x 0.15 = 86The final grade is 86%. The weights must add to 100%; otherwise, normalize them or confirm that a category is missing.
Common mistakes
- Dividing total points by earned points instead of the reverse.
- Using
60instead of0.60as a weight. - Averaging category grades without applying their weights.
- Mixing points and percentages in the same calculation.
- Rounding every component before finding the final result.
Use the percentage calculator for a single score, or the weighted grade calculator when several categories contribute to the final grade.
Frequently asked questions
How do I convert a score to a percentage?
Divide the score earned by the maximum score and multiply by 100.
Do weighted grades have to total 100%?
Normally, yes. If they do not, check the syllabus or divide each weight by the sum of all weights before calculating.