The short answer
Percent = (questions − wrong) ÷ questions × 100. On a 20-question test every question is worth 5 points, so 3 wrong = 17 ÷ 20 = 85% (B). On 25 questions each one is worth 4 points, so 3 wrong = 88% (B+). Type the number wrong above for an instant answer, switch the scale if your school uses a 10-point or 7-point system, and print the chart to keep next to the answer key.Grading a stack of quizzes comes down to one division repeated thirty times. The EZ Grader does that division once for every possible score and lays it out as a chart — on screen, on paper, or across a whole class roster.
How to use the EZ Grader
- Choose how you count. “Count questions” is for tests where each question has the same value. “Count points” is for tests with mixed point values — enter the total points and grade by points off.
- Enter the test length. For a 25-question quiz, type 25. If each question is worth 4 points, add that too; the percent stays the same, but the chart shows points as well.
- Pick the grading scale. Standard plus/minus, 10-point, 7-point, or your own custom cutoffs (saved on your device for next time).
- Type the number wrong. The big number updates as you type. Use the − and + buttons, or the arrow keys, to step through a pile of papers.
- Print the chart to keep next to your answer key, or open class batch mode to grade the whole class at once.
The grading formula, with a worked example
Every grader chart uses the same arithmetic:
% = (total − wrong) ÷ total × 100
1 question = 100 ÷ total (points)
Worked example: a 30-question test, and a student misses 4. They answered 26 correctly. 26 ÷ 30 = 0.8667, so the score is 86.7%. On the standard plus/minus scale that is a B (83–86.9); with “Assign the letter from the rounded percent” on and 0 decimals, it rounds to 87% and becomes a B+. Each question on this test moves the grade by 100 ÷ 30 = 3.33 points.
Half credit works the same way. If that student also earned half credit on one of the four, they have 3.5 wrong: 26.5 ÷ 30 = 88.3% (B+).
Grading chart for common test lengths
The table shows what each number wrong is worth on the most common quiz and test lengths, using the standard plus/minus scale.
| Wrong | 10 questions | 20 questions | 25 questions | 30 questions | 40 questions | 50 questions |
|---|---|---|---|---|---|---|
| 0 | 100% A+ | 100% A+ | 100% A+ | 100% A+ | 100% A+ | 100% A+ |
| 1 | 90% A− | 95% A | 96% A | 96.7% A | 97.5% A+ | 98% A+ |
| 2 | 80% B− | 90% A− | 92% A− | 93.3% A | 95% A | 96% A |
| 3 | 70% C− | 85% B | 88% B+ | 90% A− | 92.5% A− | 94% A |
| 4 | 60% D− | 80% B− | 84% B | 86.7% B | 90% A− | 92% A− |
| 5 | 50% F | 75% C | 80% B− | 83.3% B | 87.5% B+ | 90% A− |
| 6 | 40% F | 70% C− | 76% C | 80% B− | 85% B | 88% B+ |
| 8 | 20% F | 60% D− | 68% D+ | 73.3% C | 80% B− | 84% B |
Notice how unforgiving short quizzes are: on a 10-question quiz a single mistake costs a full letter step. If short quizzes carry real weight in your gradebook, consider adding questions or grading them for completion.
How many can a student miss and still pass?
A quick way to read any test: the number of wrong answers allowed for each cutoff is the test length times the share you can lose. For a 90% A−, students can lose 10%; for a 70% C−, 30%.
| Test length | Most wrong for 90% | for 80% | for 70% | for 60% |
|---|---|---|---|---|
| 10 | 1 | 2 | 3 | 4 |
| 20 | 2 | 4 | 6 | 8 |
| 25 | 2.5 | 5 | 7.5 | 10 |
| 30 | 3 | 6 | 9 | 12 |
| 40 | 4 | 8 | 12 | 16 |
| 50 | 5 | 10 | 15 | 20 |
On a 25-question test the cutoffs land on half questions, which is one reason half credit matters: without it, a student with 3 wrong drops straight from 92% to 88%.
How do I make an easy grader chart for 25 questions with half points?
On a 25-question test each question is worth 100 ÷ 25 = 4 percentage points, so a half point is worth 2. That makes 25 one of the friendliest lengths for half credit: every row lands on a whole percent. Set the test length to 25, tick “Allow half credit” and “Show half steps”, and the grader chart prints rows like these.
EZ Grader chart for 25 questions with half steps, standard plus/minus scale
| Wrong | Correct | Percent | Letter |
|---|---|---|---|
| 0 | 25 | 100% | A+ |
| 0.5 | 24.5 | 98% | A+ |
| 1 | 24 | 96% | A |
| 1.5 | 23.5 | 94% | A |
| 2 | 23 | 92% | A− |
| 2.5 | 22.5 | 90% | A− |
| 3 | 22 | 88% | B+ |
| 3.5 | 21.5 | 86% | B |
| 4 | 21 | 84% | B |
| 4.5 | 20.5 | 82% | B− |
| 5 | 20 | 80% | B− |
| 5.5 | 19.5 | 78% | C+ |
| 6 | 19 | 76% | C |
| 6.5 | 18.5 | 74% | C |
| 7 | 18 | 72% | C− |
Grading by number correct. If you mark the right answers instead of the wrong ones, read the “Correct” column, or multiply: on 25 questions, percent = correct × 4, so 21 correct is 84%. The multiplier is always 100 ÷ total, which is 5 on a 20-question quiz and 2 on a 50-question test. Both directions give the same grading percentage; pick whichever is faster to count on the paper.
Where half credit decides the letter. A student with 2.5 wrong keeps an A− at exactly 90%, while 3 wrong drops to a B+ at 88%. If several students land just under a cutoff, look for one confusing question before reaching for the grade curve calculator. Students who want to check a single paper at home can use the quiz and test grade tool, and the 10-point grading scale comparison shows how the same rows read under other cutoffs.
Printing a one-page grading chart
Press Print chart and only the chart goes to the printer — no menus, no article text. The chart splits itself into up to six columns and shrinks its rows so that a test of up to a few hundred rows fits on a single Letter or A4 sheet. The title line records the test length, points per question and scale, so a chart found in a drawer next semester still makes sense.
For the cleanest printout, set the decimals first: 0 decimals keeps the columns narrow, 1 decimal is the usual choice for tests that don’t divide evenly. If you turn on half steps for a long test, the chart doubles in length; the note under the chart tells you if it will no longer fit on one page.
Grading a whole class with batch mode
Open Class batch mode and type one student per line: a first name or initials if you like, then a comma and the number wrong (or the score, or the percent — pick in the menu). You get each student’s percent and letter, the class average with its letter, the median, the highest and lowest score, and a bar chart of the letter distribution. Download CSV gives you a spreadsheet you can paste into your gradebook.
The median is worth a glance next to the average: if one student scored 30% on a test where everyone else landed in the 80s, the average drops noticeably while the median barely moves. If the whole class scored lower than you expected, look at the grade curve calculator before adjusting anything, and check which questions most students missed.
Batch mode handles up to 40 students. Names stay in this browser tab and disappear when you close it.
Related tools for grading day
- Turning a rubric into points first? Build it in the rubric maker.
- Averaging several tests for a term grade: the average grade calculator.
- Writing the report card afterward: the report card comment generator.
- Students asking what they need on the final can use the final grade calculator.
Teachers have kept grade charts like this taped inside gradebooks for decades. This one simply does the rows for you.
Frequently asked questions
How does an EZ Grader work?
How do I grade a test with half credit?
What if my questions are worth different points?
Should 89.5% round up to an A−?
Does the class batch mode save my students' names?
How do I grade by number correct instead of number wrong?
How do I make an easy grader chart for 25 questions?
Is this easy grader free to use?
Sources & method
- Formula: percent correct = (total − wrong) ÷ total × 100; all tables on this page are computed from it.
- Scales: standard plus/minus (A+ 97, A 93, A− 90, B+ 87…), 10-point (90/80/70/60) and 7-point (93/85/77/70) are common US cutoffs, not universal rules. Check your district’s policy, or compare scales in our grading scale converter.
Formulas checked October 2026. Spotted an error? Tell us via the about page.