How to Calculate a Test Grade
The formula, letter grade scale, GPA equivalents, and worked examples — everything you need to convert any test score to a percentage and letter grade in seconds.
The Test Grade Formula
Every test grade comes down to one formula:
You earned 43 points on a 55-point test. Your grade is (43 ÷ 55) × 100 = 78.2% — a C+ on the standard US scale.
The formula works for any scoring system: points, out of 10, out of 20, out of 50, or out of 100. Whatever the total, divide your score by it and multiply by 100. The result is always a percentage between 0 and 100 (or higher if extra credit is involved).
Worked examples at a glance
| Score | Total | Calculation | Grade % | Letter |
|---|---|---|---|---|
| 38 | 45 | 38 ÷ 45 × 100 | 84.4% | B |
| 27 | 40 | 27 ÷ 40 × 100 | 67.5% | D+ |
| 18 | 20 | 18 ÷ 20 × 100 | 90.0% | A- |
| 7 | 10 | 7 ÷ 10 × 100 | 70.0% | C- |
| 55 | 60 | 55 ÷ 60 × 100 | 91.7% | A- |
| 88 | 100 | 88 ÷ 100 × 100 | 88.0% | B+ |
You can verify any of these instantly with the grade calculator — enter your score and the total and it converts it immediately.
The standard US letter grade scale
Most US schools use the following 13-grade scale. Each letter grade covers a 3-percentage-point range, except for A+ (97–100) and F (below 60).
| Letter Grade | Percentage Range | GPA Points (4.0 scale) | Descriptor |
|---|---|---|---|
| A+ | 97–100% | 4.0 | Exceptional |
| A | 93–96% | 4.0 | Excellent |
| A− | 90–92% | 3.7 | Excellent |
| B+ | 87–89% | 3.3 | Above average |
| B | 83–86% | 3.0 | Good |
| B− | 80–82% | 2.7 | Good |
| C+ | 77–79% | 2.3 | Average |
| C | 73–76% | 2.0 | Average |
| C− | 70–72% | 1.7 | Average |
| D+ | 67–69% | 1.3 | Below average |
| D | 63–66% | 1.0 | Below average |
| D− | 60–62% | 0.7 | Below average |
| F | 0–59% | 0.0 | Failing |
Note that this is the most common US scale but not universal. Some schools start the F threshold at 65% rather than 60%, or collapse the plus/minus grades into a 5-grade system (A, B, C, D, F). Always check your school’s official grading policy — particularly for determining what counts as a passing grade.
Questions with different point values
The formula is unchanged when a test mixes question types worth different amounts. You still divide total points earned by total points possible. For a test with 10 multiple-choice questions worth 2 points each (20 pts) and 4 essay questions worth 10 points each (40 pts), total possible is 60 points. If you scored 16 on multiple choice and 34 on essays, your total is 50 ÷ 60 × 100 = 83.3% — a B.
The only time this gets tricky is when grades are reported as separate category percentages rather than combined points. In that case you’re dealing with a weighted grade, not a simple test score.
Extra credit and grades above 100%
Extra credit adds points to your numerator without increasing the denominator. If a 50-point test offers 5 points of extra credit and you earned 47 regular points plus 4 bonus points, your grade is (47 + 4) ÷ 50 × 100 = 102%. This is entirely valid. Extra credit is designed to let students exceed the base maximum, so a grade above 100% is the intended outcome.
Whether and how extra credit appears on your transcript depends on the school. Some institutions cap the reported grade at 100% even when the calculated grade exceeds it. Others let the extra credit carry over to raise a weighted category grade, which means the benefit shows up in your overall course grade rather than the individual test percentage.
Understanding curved grades
When a test is unexpectedly difficult, teachers sometimes “curve” the grades upward. The three most common methods are: (1) flat addition — every student gets the same number of bonus points added; (2) square root curve — your percentage is replaced with its square root × 10 (so 64% becomes √64 × 10 = 80%); (3) scale to highest score — everyone’s score is multiplied by 100 ÷ highest score in the class, so if the top score was 88, everyone is multiplied by 1.136.
A curve always benefits students, but the amount varies by method. The flat-addition curve is the most transparent. The scale-to-highest method rewards everyone equally relative to the strongest student. Either way, applying a curve does not change the formula — it changes the inputs. Once you know your curved score, Grade % = (Curved Score ÷ Total) × 100 as normal.
Mental math shortcuts for fast estimation
When you don’t have a calculator: if your test is out of 100, your score is already a percentage. For other totals, use these shortcuts. Out of 50: double your score (score × 2 = percentage). Out of 20: multiply by 5. Out of 25: multiply by 4. Out of 10: multiply by 10. For totals that aren’t round numbers, round up to the nearest easy number first to get an estimate, then refine. A score of 38 out of 47 — treat it as 38 out of 50 (76%), then adjust upward slightly because the real denominator is smaller: the actual grade is 80.9%.
These shortcuts are also useful for checking whether an answer from a calculator is in the right ballpark. If you calculated a 95% for a score of 38 out of 55, the shortcut (38 out of 50 = 76%) tells you immediately that 95% is wrong — you likely divided in the wrong order.
Frequently Asked Questions
Divide your points earned by the total points possible, then multiply by 100. Formula: Grade % = (Points Earned ÷ Total Points) × 100. Example: 43 out of 55 = (43 ÷ 55) × 100 = 78.2%. You can also use the grade calculator to do this instantly.
78% is a C+ on the standard US grading scale. The C+ range is 77–79%. A 78 is solidly passing but just below a B-minus (80%). On a 4.0 GPA scale, a C+ is typically worth 2.3 grade points.
A B (83–86%) is worth 3.0 on the 4.0 GPA scale. A B+ (87–89%) = 3.3, and a B− (80–82%) = 2.7. Most colleges consider a 3.0 GPA (B average) the threshold for maintaining good academic standing in competitive programs.
43 out of 55 is 78.2%. Formula: (43 ÷ 55) × 100 = 78.18%, which rounds to 78.2%. That falls in the C+ range (77–79%) on the standard US letter grade scale.
Add your extra credit points to your earned points before dividing. Formula: Grade % = ((Points Earned + Extra Credit) ÷ Total Points) × 100. Example: 42 earned + 4 extra credit on a 50-point test = (46 ÷ 50) × 100 = 92%. Extra credit can push your grade above 100% if enough is offered.
Curving adjusts scores upward when a test was too difficult. Common methods: flat point addition (+7 to every score), scaling so the top score becomes 100% (multiply everyone by 100 ÷ top score), or adjusting letter grade cutoffs. Always ask which method your teacher uses since the grade benefit differs significantly between them.
The formula is the same — add up all points earned across all questions and divide by the total points possible. For a test with five 4-point questions and three 10-point questions: total = 5×4 + 3×10 = 50 points. If you earned 38 total: (38 ÷ 50) × 100 = 76%.
A B average requires 83% or higher overall (the B range is 83–86%). To maintain a B across multiple tests, track your running total points earned vs points possible and calculate your running percentage. You can also use the final exam grade calculator to find exactly what score you need on a remaining test to reach your target.