Most schools calculate a grade in three steps: they combine your scores into one percentage, they apply any weights or dropped scores, and then they convert the percentage into a letter using the school’s grading scale. What differs from class to class is how the scores are combined: some teachers pool points, and others weight categories.

If you want the basic arithmetic first, start with our guide on how to calculate grades step by step. If you want to see how the final letter is chosen, read grading scales explained. This guide connects the two and shows how a real gradebook works.

The three steps behind a grade

1. Score each assignment. Every test, quiz, project or homework gets points or a percentage.
2. Combine the scores. The gradebook turns many scores into one percentage, either by pooling points or by weighting categories, and applies rules such as a dropped lowest score.
3. Convert to a letter. The school’s grading scale decides which letter and which grade points the percentage earns.

The second step is where most of the variation happens, so the rest of this guide focuses on it.

Points-based gradebooks

In a points-based gradebook, every assignment is worth a number of points, and the grade is simply the total earned divided by the total possible. A 100-point project counts for five times as much as a 20-point quiz, because it has five times the points.

Take a student with 45 out of 50 on homework, 18 out of 20 on a quiz, 88 out of 100 on a project and 72 out of 80 on a test. The total is 223 out of 250 points. To get the percentage, divide earned by possible and multiply by 100, or let the percentage calculator do it: 223 ÷ 250 × 100 = 89.2%.

This method is easy to follow, and a student can check it with nothing more than the points shown in the gradebook.

Weighted gradebooks

In a weighted gradebook, assignments are sorted into categories, such as homework, quizzes, tests and projects, and each category counts for a fixed share of the grade. The steps are:

1. Work out the percentage inside each category, using the points in that category only.
2. Multiply each category percentage by its weight.
3. Add the results. The weights should add up to 100%.

The weights are what make a weighted gradebook different. A category worth 40% of the grade moves the result twice as much as a category worth 20%, no matter how many points each category has. You can try this with the weighted grade calculator, and our guide to how weighted grades work goes through the maths in more depth.

A full gradebook example

Here is a gradebook with four weighted categories. The student’s scores are:

• Homework (20%): 45/50, 38/40 and 28/30, a total of 111 out of 120.
• Quizzes (20%): 18/20, 19/20 and 16/20, a total of 53 out of 60 (after the lowest quiz is dropped).
• Tests (40%): 72/80 and 85/100, a total of 157 out of 180.
• Projects (20%): 88/100.

Each “points toward grade” figure is the category score multiplied by its weight. For tests, 87.22% × 0.40 = 34.89. Adding the four figures gives 18.50 + 17.67 + 34.89 + 17.60 = 88.66, so the course grade is about 88.7%.

If the same student’s points had simply been pooled, the grade would be 409 ÷ 460 = 88.9%. The two methods give slightly different answers because the weights give tests a bigger share than their points do. That is why you should always find out which method your teacher uses.

Dropping the lowest score

Many teachers drop the lowest score in a category, often for quizzes or homework, so that one bad day does not drag down a whole term. The category is then calculated as if that assignment did not exist.

In the example above, the student actually took four quizzes: 18/20, 12/20, 19/20 and 16/20. Counting all four gives 65 ÷ 80 = 81.25%. Dropping the 12 leaves 18 + 19 + 16 = 53 out of 60, which is 88.33%. One dropped score lifted the category by about seven points. If your teacher has a drop policy, make sure you know which categories it applies to, and how many scores are dropped.

Term grades vs cumulative grades

A term grade covers one marking period, such as a quarter or a semester. A cumulative grade covers the whole course so far, and it keeps changing as new work is graded. Some online gradebooks show the cumulative grade all year, and others reset at the start of each term.

Schools also combine term grades into a final grade in different ways. One common pattern is to count each of two terms for 40% and the final exam for 20%. A student with 90% in the first term, 86% in the second and 80% on the exam would get 0.40 × 90 + 0.40 × 86 + 0.20 × 80 = 36 + 34.4 + 16 = 86.4%. Your own school may use other weights, so check the handbook.

Turning the percentage into a letter

The last step is the grading scale. The 88.7% from the example becomes a B on the standard 10-point scale, a B+ on the plus/minus scale and a B on the 7-point scale. Enter your own percentage in the letter grade calculator and choose the scale your school uses. Keep the full decimal until this last step, and round only if your teacher’s policy says so.

Other ways to build a grade

Not every grade starts as a pile of points. In some classes, especially for writing, projects and performances, teachers score the work against a rubric with levels such as 1 to 4. Some schools report those levels directly, and others convert them into percentages for the gradebook. Our comparison of rubric vs percentage grading explains how each method works and when to use it.

Why your grade may differ from your own calculation

If your number does not match the gradebook, check these common causes:

• Different weights. The syllabus weights may not match what you assumed.
• A dropped score that you counted, or one you forgot was dropped.
• Missing work that the gradebook counts as a zero.
• Pooled points vs averaged percentages. The two methods give different results.
• Extra credit or late penalties that change the points possible or earned.
• Rounding. The gradebook may round the final number differently from you.

To check your own grade, list your scores by category, work out each category percentage, apply the weights and any drop rule, and compare the result with the gradebook. If it still differs, ask your teacher to walk through the calculation.

Frequently asked questions

How do teachers calculate final grades?

They combine all scores into one percentage, either by adding up points or by weighting categories, apply any drop or extra credit rules, and then convert the percentage to a letter using the grading scale.

Do schools use points or weights?

Both are common. Some teachers use total points, and others use weighted categories. Your syllabus or gradebook settings will say which one applies in your class.

How does a dropped lowest score work?

The lowest score in a category is removed, and the category is calculated from the remaining scores. For example, quiz scores of 18, 12, 19 and 16 out of 20 become 53 out of 60 after the 12 is dropped.

What is the difference between a term grade and a cumulative grade?

A term grade covers one marking period. A cumulative grade covers the whole course so far and keeps updating as new work is graded.

Why does my gradebook show a different grade from my calculation?

Common reasons are different weights, dropped scores, missing assignments counted as zero, pooled points versus averaged percentages, extra credit or rounding. Ask your teacher to explain the calculation.