Every calculator on this site runs one of the formulas below, in your browser. The code that does it is small enough to read, and this page shows the working so you can check any result by hand.
Letter grades
All calculators use the most common US letter scale. Your school may set different cut-offs, and if it does, its scale is the one that counts.
| Letter | Percent | Points (4.0 scale) | Points (4.3 scale) |
|---|---|---|---|
| A+ | 97 to 100 | 4.0 | 4.3 |
| A | 93 to 96 | 4.0 | 4.0 |
| A- | 90 to 92 | 3.7 | 3.7 |
| B+ | 87 to 89 | 3.3 | 3.3 |
| B | 83 to 86 | 3.0 | 3.0 |
| B- | 80 to 82 | 2.7 | 2.7 |
| C+ | 77 to 79 | 2.3 | 2.3 |
| C | 73 to 76 | 2.0 | 2.0 |
| C- | 70 to 72 | 1.7 | 1.7 |
| D+ | 67 to 69 | 1.3 | 1.3 |
| D | 63 to 66 | 1.0 | 1.0 |
| D- | 60 to 62 | 0.7 | 0.7 |
| F | below 60 | 0.0 | 0.0 |
A boundary is inclusive: 90.0 is an A-, 89.99 is a B+. The letter is chosen from the unrounded percentage, so a 92.96 shows as 93.0 percent but stays an A-.
Grade calculator
Each assignment is turned into a percentage (score divided by what it was out of), multiplied by its weight, and averaged.
percent = sum(score / out_of x 100 x weight) / sum(weight)
Weight defaults to 1 when left blank. Rows with no score, an "out of" of zero, or a negative weight are skipped. Example: 45 out of 50 (weight 1) and 80 out of 100 (weight 1) gives (90 + 80) / 2 = 85 percent, a B.
Weighted grade calculator
Each category has an average and a weight. Categories with no average yet are left out, and the remaining weights are scaled to add up to 100. That is what "current standing" means part-way through a term.
percent = sum(average x weight) / sum(weight of categories that have an average)
Example: homework 90 (weight 20), midterm 80 (weight 30), final blank (weight 50). Only the first two count: (90 x 20 + 80 x 30) / (20 + 30) = 84 percent. The calculator tells you when it has scaled the weights, and when your weights do not add to 100.
Final grade calculator
Your course grade is the part already earned plus the part the final decides. Solving for the final's score gives:
required = (target - current x (1 - w)) / w, where w is the final's weight as a decimal.
Example: current 88, target 90, final worth 20 percent. (90 - 88 x 0.8) / 0.2 = (90 - 70.4) / 0.2 = 98. A result above 100 means the target cannot be reached on the final alone. A result at or below 0 means you already have it. The calculator also shows the range of possible course grades: current x (1 - w) if the final scores 0, and current x (1 - w) + 100 x w if it scores 100.
Easy grader
percent = (questions - wrong) / questions x 100
Example: 20 questions, 3 wrong: 17 / 20 x 100 = 85 percent, a B. The chart lists every possible number wrong for that test length. Percentages display to one decimal place; the letter uses the exact value.
GPA calculator
Each course's grade points are multiplied by its credits, added up, and divided by the total credits. A course with more credits moves the GPA more.
GPA = sum(points x credits) / sum(credits)
Example: A (3 credits), B+ (4 credits), C (3 credits). Points: 4.0 x 3 = 12, 3.3 x 4 = 13.2, 2.0 x 3 = 6. Total 31.2 over 10 credits = 3.12.
Credits default to 1 when left blank, which is right for most high-school transcripts. If you enter a percentage instead of a letter, it is converted to a letter with the table above first, then to points.
Cumulative GPA
A prior GPA and the credits it covers are folded in as if they were one more course:
cumulative = (prior_GPA x prior_credits + sum(points x credits)) / (prior_credits + sum(credits))
Example: a 3.0 over 45 credits, then a 4.0 term over 15 credits: (135 + 60) / 60 = 3.25.
Weighted high-school GPA
The high-school calculator adds a bonus to the grade points before multiplying by credits: honors +0.5, AP +1.0, IB +1.0. An A in an AP class is 5.0. Districts differ; some cap weighted GPAs at 4.5, some use a 6.0 scale, and some do not weight at all. Both the weighted and unweighted figures are shown so you can read whichever your school uses.
Rounding
Percentages are shown to one or two decimal places and GPAs to two. Rounding happens only when a number is displayed, never in the middle of a calculation, so chaining results by hand may differ from the calculator by a hundredth.
Checking the code
All of the formulas above live in a single file that the site loads, /source/grade.js, and each one has an automated test. If you find a result you think is wrong, tell us with the inputs you used.