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Different question values? Add their points first. Extra credit can take the score above 100%.
What is 20 out of 30 as a percentage?
To find 20 out of 30 (20/30) as a percentage, divide 20 by 30 and multiply by 100: 20 ÷ 30 × 100 ≈ 66.67%, a D on the common US plus/minus scale. Rounded to 2 decimal places.
Letter scale: Common US plus/minus scale
The plus/minus cutoffs Wikipedia lists for US colleges: A+ from 97%, A 93, A- 90, B+ 87, B 83, B- 80 and so on down to D- at 60. It is not universal, so use your syllabus's cutoffs when they differ. Source: Wikipedia, “Academic grading in the United States”.
| Letter | Lowest % | Remove |
|---|
Each letter starts at its lowest percentage and runs up to the next letter.
Rounding and decimal places
Follow your syllabus. A displayed percentage can round up while the unrounded score stays below a cutoff.
Only changes how results are shown. Extra places appear when rounding would push a score over a letter cutoff.
A letter typed as a score counts as the lowest percentage for that letter on this scale. Use the original percentage when you have it.
Check a single cutoff with the grading scale calculator.
Grading scales checked . Sources are at the bottom of the page.
The fraction, decimal and missing points
20/30 = 2/3 ≈ 0.666667
Divide 20 earned points by 30 possible points, then multiply by 100 to get 66.67%. 30 − 20 = 10 points missed.
Or count by points: each point is worth 100 ÷ 30 ≈ 3.3333%, so 20 × 3.3333 ≈ 66.67%.
The letter above uses the common US plus/minus scale. Your class may set other cutoffs: open “Letter scale” above to choose another scale or enter your own. For the general method, see how to turn points into a percentage.
What does one more point change?
| Points earned | Percentage | Points missed |
|---|---|---|
| 19 out of 30 | ≈ 63.33% | 11 |
| 20 out of 30 | ≈ 66.67% | 10 |
| 21 out of 30 | 70% | 9 |
≈ means rounded to 2 decimal places.
One point changes this score by 3.3333 percentage points. The denominator stays 30.