To calculate a grade, divide the points you earned by the points that were possible, then multiply by 100. A student who scores 22 out of 25 has 22 ÷ 25 × 100 = 88%. That one formula covers most tests, quizzes and assignments.

It gets trickier when a class adds up many assignments, when you only know how many answers were wrong, or when different categories count for different amounts. This guide walks through each case with worked examples. Whether you are a teacher grading a stack of papers or a student checking a gradebook, the steps are the same, and each section points to a free calculator so you can check your own numbers.

The basic grade formula

Every percentage grade comes from comparing what a student got with what was available. Written as a formula:

“Points earned” is the number of correct answers, or the marks a student received. “Points possible” is the total on the test or assignment. Dividing the two gives a decimal between 0 and 1, and multiplying by 100 turns it into a percentage.

For example, if a student answers 22 questions correctly on a 25-question test, 22 ÷ 25 = 0.88, and 0.88 × 100 = 88%. If you would rather skip the arithmetic, the percentage calculator does it for you and shows the working underneath the answer.

Here are a few common test sizes, so you can see how the score changes:

How to calculate a grade step by step

1. Find the points possible. This is the total number of questions or marks on the test or assignment.
2. Find the points earned. Count the correct answers, or add up the marks. Include partial credit if your teacher gives it.
3. Divide earned by possible. Use a calculator and keep all the decimals.
4. Multiply by 100. This gives the percentage.
5. Round last. Rounding in the middle of a calculation adds small errors. If your result sits right on a boundary, such as 89.5%, see how grade rounding works.

Here is an example with partial credit. A student earns 41.5 points on a 50-point assignment: 41.5 ÷ 50 = 0.83, and 0.83 × 100 = 83%.

Method 1: calculate a grade from total points

Many classes pool all the points a student earns across the term. In that case, you add up every point earned, add up every point possible, and divide once. Larger assignments count for more automatically, because they carry more points.

Working: 223 ÷ 250 = 0.892, so the grade is 89.2%. Notice that the project (100 points) moves the result more than the quiz (20 points). That is exactly what you want when the syllabus says the grade is based on total points.

Calculating a grade from wrong answers

Teachers often count mistakes rather than correct answers. You can still use the same formula. First work out how many answers were right:

On a 25-question test with 3 wrong answers, there are 25 − 3 = 22 correct answers, and 22 ÷ 25 × 100 = 88%.

There is also a handy shortcut. Each question is worth 100 ÷ total questions percentage points. On a 20-question test, every question is worth 5%, so each wrong answer takes 5% off. On a 25-question test it is 4% per question, on a 50-question test it is 2%, and on a 100-question test it is 1%.

When you are marking a whole class, doing this by hand gets slow. The Easy Grader is built for exactly this job: enter the total number of questions, tap +1 Wrong for each mistake, and read the percentage and letter grade straight away. New to it? Read what an easy grader is. Planning ahead for a test? See how many questions you can miss and still reach the grade you want.

Method 2: average of percentages, and why it can differ

Some teachers average the percentage of each assignment instead of pooling the points. The two methods can give different answers, and the gap is bigger when the assignments are different sizes.

Suppose a student scores 10 out of 10 on a quiz and 60 out of 100 on a test.

The simple average treats the 10-point quiz and the 100-point test as equally important. Total points gives the test ten times the influence, because it has ten times the points. Neither is “wrong”. What matters is which one your teacher or school uses, and the syllabus or gradebook settings will tell you.

Method 3: weighted grades

In a weighted system, grades are split into categories, such as tests, homework and projects, and each category counts for a set percentage of the final grade. First work out your average in each category (using Method 1 inside the category). Then apply the weights:

Weights are written as decimals in the formula, so 50% becomes 0.50. They should add up to 100%. Here is an example:

Working: 41.0 + 19.0 + 17.6 + 10.0 = 87.6, so the final grade is 87.6%. The student did very well in homework and participation, but the tests carry half the grade, so the result sits closer to the test score than to the homework score.

The weighted grade calculator does all of this as you type, and warns you if your weights do not add up to 100%. To go deeper on the idea, read our guide to weighted grades.

What if a category has no grades yet?

Partway through a term, some categories are still empty. Do not count them as zero. Instead, use only the categories that have grades and divide by the total weight you used:

Say the student above has tests (82% at 50%) and homework (95% at 20%), but no projects or participation grade yet. The points earned are 41.0 + 19.0 = 60.0, and the weights used add up to 70%. So the current grade is 60.0 ÷ 0.70 = 85.7%. This is your grade so far, and it will move as the other categories are graded.

Converting a percentage to a letter grade

Once you have a percentage, the last step is often turning it into a letter. The most common US scale is the 10-point scale:

Not every school uses this scale. Some split each letter into plus and minus, and some use a 7-point scale where an A starts at 93%. The same 92% can be an A on one scale, an A− on another and a B on a third. Read about each grading scale before you compare grades, and use the letter grade calculator to convert a percentage on the scale your school uses.

Working backwards: how many points do you need?

Sometimes you know the grade you want and need to find the score. Rearrange the formula:

To get 90% on an 80-point test, you need 0.90 × 80 = 72 points. To reach 85% on a 25-question test, you need 0.85 × 25 = 21.25 correct answers. You cannot answer a quarter of a question, so always round the points needed up. Here that means 22 correct answers. With 21 correct you would have 84%, which falls just short.

Percentage, letter grade and GPA

These three are related but not the same. A percentage is the direct result of the formula. A letter grade is a label for a range of percentages, so 88% and 82% can both be a B. GPA then turns letters into grade points, such as 4.0 for an A, and averages them across courses, usually counting each course by its credit hours. Every step drops a little detail, which is why two students with different percentages can end up with the same letter.

Common mistakes when calculating grades

• Using the wrong total. If a question was thrown out, or the test had bonus points, the points possible change. Use the total that was actually graded.
• Rounding too early. Keep the full decimal until the final answer.
• Averaging percentages when points are pooled. As the quiz and test example showed, this can overstate or understate the real grade.
• Weights that do not add up to 100%. If they add to 90% or 110%, the final grade is off unless you scale it.
• Typing a weight as 0.4 instead of 40. Check whether a tool wants a percentage or a decimal.
• Assuming every school uses the same letter scale. Check the syllabus first.

Tips for teachers and students

For teachers

• Say on day one whether the class uses total points or weighted categories.
• Publish your rounding rule, so nobody is surprised by a borderline grade.
• Use a calculator for stacks of tests. It is faster and avoids arithmetic slips.

For students

• Keep your own running record of points earned and points possible.
• Check your gradebook against your own numbers once a month.
• Ask your teacher which method the class uses if the syllabus does not say.

Free grade calculators

You do not have to do any of this by hand. Pick the calculator that matches your situation:

Results are for guidance only. Always confirm official grades with your school or instructor.

Frequently asked questions