The grade percentage formula
Grade % = points earned ÷ points possible × 100
This works for any graded item: a test, an essay scored with a rubric, a lab report or a whole class graded on total points.
Worked example
An essay scored on a 40-point rubric
You earned 34 of 40: 34 ÷ 40 × 100 = 85%, a B. For an A- you'd need 0.90 × 40 = 36 points.
From percentage to letter grade
Most U.S. schools convert percentages with a 10-point plus/minus scale: 90–100 is an A range, 80–89 a B range, 70–79 a C range, 60–69 a D range and below 60 an F. Inside each range, the top three points are a plus (e.g. 87–89 = B+) and the bottom three a minus (80–82 = B-). The full table is on the grading scale page.
Common score conversions
| Score | Percentage | Letter |
|---|---|---|
| 15 out of 20 | 75% | C |
| 17 out of 20 | 85% | B |
| 12 out of 15 | 80% | B- |
| 13 out of 15 | 86.67% | B |
| 21 out of 25 | 84% | B |
| 24 out of 30 | 80% | B- |
| 43 out of 50 | 86% | B |
| 45 out of 50 | 90% | A- |
A grade calculator with percentages for the whole class
This page converts one score at a time. For a grade calculator with percentages across a whole class, where you enter every assignment's percentage and weight, use the main grade calculator.
When percentages aren't the whole story
One assignment's percentage isn't your class grade. In a weighted class, a 75% on a quiz worth 5% matters far less than a 75% on a test worth 30%. To see your overall grade, enter your scores in the grade calculator. To average several percentages equally, use the average grade calculator.
Frequently asked questions
How do I calculate a grade percentage?
What percentage is a 15 out of 20?
How do I find how many points I need for an A?
Can a grade percentage be over 100%?
Is a grade percentage the same as a percentile?
Last reviewed by the GradeCalc team. See how we calculate.