A score of 13 out of 15 on a test, assignment or class is a 86.67% percentage grade. 2 questions were wrong or points missed.
A 86% is a B letter grade. A letter grade B means good or above average performance. The teacher may round up the 86.67% to a 87% for a B+ letter grade.
The grade point equivalent to a B is a 3.0 GPA for this score. If rounding up to a B+, the GPA is a 3.3.
| Grade | Correct | Incorrect | Percent |
|---|---|---|---|
| A+ | 15 | 0 | 100.00 |
| A | 14 | 1 | 93.33 |
| B | 13 | 2 | 86.67 |
| B- | 12 | 3 | 80.00 |
| C | 11 | 4 | 73.33 |
| D | 10 | 5 | 66.67 |
| D- | 9 | 6 | 60.00 |
| F | 0 to 8 | 7 to 15 | 0.00 to 53.33 |
This easy grade calculator can be used for quickly determining the percentage, letter grade and GPA for any test, quiz or exam. It can also be used when calculating an overall score in a class. This page is pre-populated showing the results for the particular calculation 13/15 as a percentage and as a grade. You can access the default calculator here.
To use, input the total number of questions or maximum points available in the "Questions" field. Next either enter the number of correct or incorrect answers in the respective fields. You only need to enter one, the other one will calculate automatically. Your results will appear as you type.
The result will compute the score as a percentage, the letter grade for the score and the GPA for the letter grade. The calculator will also indicate when a score is within one percent of the breakpoint between letter grades where it is appropriate to round up the grade.
Additionally you will see a letter grading scale table which shows every letter grade available for the number of questions on the test. This table indicates the correct and incorrect ranges for each letter grade along with the percentage ranges. Note that on some tests, letter grades are skipped - this is not a mistake. This happens on tests with fewer questions as each question is worth a significant percent of the overall score and significantly moves the letter grade.
A score of 13/15 equates to a B. A B is a good grade and demonstrates you know the class material well. Traditionally a B means "above average", however in reality it's about average for most high school students.
13 out of 15 is right on the border between a B and a B+. It's equal to a 86.67% which is technically a B. Because it's only 0.33 percentage points away from a B+, your teacher may give you a break and award you a B+.
The math is pretty simple to determine the percentage grade on a test as it's simple division and multiplication. The ratio of correct to total number of questions can be expressed as a fraction
correct answers / total questions
The fraction is converted into a decimal using correct answers as the numerator and total questions as the denominator. Divide the correct answers by total questions and you have the answer in decimal form.
correct answers ÷ total questions = decimal
Now to convert into a percent, multiply the decimal times 100. This is your answer.
decimal × 100 = percent answer
In this particular case, the formula for calculating the grade percent 13/15 is
13 ÷ 15 × 100 = 86.67%
On a 15 question test, if you miss 2 and get 13 right, you will have a 86.67%.
To determine the letter grade, we must make use of a letter grade scale lookup table. You can find one here.
Take the percentage calculated for the test and locate the corresponding range in the percent column. The letter grade for that row is the letter grade for this test.
For this score, we find our 86.67% is in the 83-86% range. This corresponds with the letter grade "B". Thus, a 86.67% grade is a B.