Grade Percentage Calculator
Last updated: November 14, 2026
Direct answer. To turn a test score into a percentage, divide the points you earned by the points possible and multiply by 100. 17 out of 20 is (17 ÷ 20) × 100 = 85%.
Turn the points on a quiz, unit test, midterm, or homework assignment into a percentage, and see how many points were left on the table. This is the same (earned ÷ possible) × 100 math used on countless U.S. score reports.
Grade Percentage Calculator
Turn points earned on a test, quiz, or assignment into a percentage, and see how many points remain.
Result
Key takeaways
- Grade percentage = (Points earned ÷ Points possible) × 100.
- The unit is a percentage of the assignment, not a letter grade. Letter cutoffs vary by school.
- 17 out of 20 is 85%, with 3 points remaining.
- A possible score of 0 cannot be converted, because that would divide by zero.
How to use this calculator
- Enter the points earned — the number your instructor recorded as correct or awarded.
- Enter the points possible for that assignment, including extra credit only if it is part of the official denominator.
- Read the percentage and the points remaining. The working is listed under the result.
The formula
A test percentage is a part-to-whole comparison. Both numbers should use the same unit, usually raw points.
Worked examples
| Points earned | Points possible | Percentage | Points remaining |
|---|---|---|---|
| 17 | 20 | 85% | 3 |
| 45 | 50 | 90% | 5 |
| 0 | 25 | 0% | 25 |
| 50 | 50 | 100% | 0 |
Divide 17 by 20 to get 0.85. Multiply by 100. The grade is 85%, and 3 points remain.
45 ÷ 50 × 100 = 90%. Five points were missed. Whether that is an A- or a B+ depends on the syllabus, not on this formula.
When this is useful in the United States
U.S. high school and college students often need a percentage before a letter is assigned. A Canvas or Google Classroom entry may already show points; this calculator makes the percent explicit when the gradebook shows only a fraction.
Parents reviewing a Friday packet can check a 17/20 spelling test the same way the teacher will, without guessing at a letter.
If two sections of a course use different point totals — a 20-point quiz and a 50-point exam — convert each to a percentage first, then use the weighted grade calculator if the syllabus gives those categories different weights.
A zero on a 25-point lab is still a defined result: 0%. That is not the same as a missing assignment your teacher later excuses from the denominator.
Common mistakes
- Dividing possible points by earned points. 20 ÷ 17 is not a grade; it is the reciprocal.
- Treating the percentage as a letter. 85% may be a B or a B+ depending on the school.
- Including extra-credit points in the numerator without checking whether they also change the denominator.
Units stay in points and percent. This tool does not convert to GPA, class rank, or a curve. If your teacher drops the lowest quiz, recalculate after that quiz is removed from both the earned and possible totals, or switch to the weighted-grade tool once each category is already a percentage. The same formula works for a 5-point exit ticket and for a 150-point final; only the two raw totals change. A percentage on a single assignment is not a running course grade. If your gradebook already mixes weighted categories, convert each category first and then use the weighted grade calculator. Extra credit policies differ: some teachers add points only to the numerator, some raise the possible total, and some park extra credit in its own category. Use the same rule the instructor will use, not a rule that merely makes the percent look larger. When two sections of a class take different versions of a test, you can still compare percentages, but you cannot compare raw points. This page will not drop the lowest score for you; remove that score from both totals and calculate again. Before you treat a result as official, compare it with the points shown in the gradebook, not with a remembered letter cutoff. If the two disagree, the denominator is usually the mismatch: extra credit, a dropped question, or a curve applied later. Reset the calculator and enter the official pair of totals again.
Frequently asked questions
How do I calculate 17 out of 20 as a percentage?
Divide 17 by 20 and multiply by 100. The result is 85%.
Does this give me a letter grade?
No. It only reports a percentage. Letter cutoffs are set by the instructor or the school. The GPA and letter-grade converter on this site uses one common U.S. scale that you can edit.
What if the possible points are 0?
The percentage is undefined, because you would be dividing by zero. The calculator shows a plain-language error instead of Infinity.
Can I use this for a test that includes extra credit?
Yes, if you use the same points possible that the teacher will use. If extra credit only adds to the numerator, leave the official possible points unchanged.