How the EZ Grader works
A teacher tool that turns 'how many did the student miss' into a percentage and a letter. Paper EZ Grader cards have been a classroom staple since the 1970s — this is the same idea, but the chart updates live as you change the question count.
The math is straightforward: (questions right ÷ total questions) × 100. A 20-question quiz with 3 wrong = 17/20 = 85% = B. The benefit of the EZ Grader format is seeing the whole chart at once — useful when you are deciding whether to drop a question, give partial credit, or curve the test up by one or two answers.
- Formula
- (right ÷ total) × 100
- Letter scale
- 10-point US (93+ = A, 90-92 = A-, ...)
- Storage
- Saved locally in your browser
- Works offline
- Yes — fully client-side after first load
Common test sizes — quick reference
Here is what each grade boundary looks like in absolute wrong-counts for the test sizes teachers ask about most:
| Test size | A (93%) | B (83%) | C (73%) | D (65%) |
|---|---|---|---|---|
| 10 questions | ≤ 0 wrong | ≤ 1 wrong | ≤ 2 wrong | ≤ 3 wrong |
| 20 questions | ≤ 1 wrong | ≤ 3 wrong | ≤ 5 wrong | ≤ 7 wrong |
| 25 questions | ≤ 1 wrong | ≤ 4 wrong | ≤ 6 wrong | ≤ 8 wrong |
| 50 questions | ≤ 3 wrong | ≤ 8 wrong | ≤ 13 wrong | ≤ 17 wrong |
| 100 questions | ≤ 7 wrong | ≤ 17 wrong | ≤ 27 wrong | ≤ 35 wrong |
Tips for fair grading
- Decide cutoffs before grading. If your school does not specify, write the scale at the top of the page so students can see how borderline answers will land.
- Watch the gap at 89/90. The B+/A- boundary is the most-contested in any class. A 89.5% rounded to 90% is an A- at most schools — the EZ Grader shows the exact decimal so you can choose.
- Pull out the bottom quartile. If many students cluster below 70%, the test (not the students) may be the issue. Drop the worst-performing question and re-grade — this calculator updates instantly when you change the total.
- Use percentages, not raw counts, when comparing sections. A 20-question quiz and a 30-question quiz cannot be averaged by points — percentages line up directly.
After the test
Once you have each test grade, combine them into a course grade. The weighted grade calculator handles syllabuses with multiple categories (homework, quizzes, tests, final). If a student is asking what they need on the final exam to hit a target, the final grade calculator works backwards from the target.
Students can then plug their course letter into a GPA calculator to see how this class affects their cumulative GPA — useful for college-bound seniors comparing semesters.
Why this is free
We make GPA and grade calculators for high school and college students. Teachers asked for an EZ Grader to use during in-class grading — so here it is. No signup, no ads in the calculator surface, no tracking of grades. Everything stays in your browser.