The EZ Grader, minus the cardboard
Every teacher knows the drill: a stack of 28 quizzes, each needing a percentage on top. The classic sliding EZ Grader chart solved this in 1964 and hasn't changed since — this page is the same idea without the slider wearing out. Type the number of questions once, and the chart shows the score for every possible number of wrong answers. Grade the whole stack reading straight off the table; the highlighted row follows the "questions wrong" box if you prefer typing each paper in.
Score steps depend on test length
Each question on an equally-weighted test is worth 100 ÷ (number of questions) points. That step size decides how forgiving a test is:
| Questions | Points per question | One wrong | Three wrong |
|---|---|---|---|
| 10 | 10 | 90% (A-) | 70% (C-) |
| 20 | 5 | 95% (A) | 85% (B) |
| 25 | 4 | 96% (A) | 88% (B+) |
| 50 | 2 | 98% (A+) | 94% (A) |
On a 10-question quiz, three careless mistakes drop a student two full letter grades; on a 50-question exam the same three mistakes still leave an A. Neither is wrong, but it's worth knowing which kind of test you're giving — short quizzes measure precision as much as knowledge.
Fast grading workflow
For a class set: set the question count, then sort papers into piles by number wrong as you mark them — don't compute anything per paper. When the stack is sorted, read each pile's score off the chart once and write it on every paper in the pile. For partial credit, tally half-wrong answers as 0.5 in your head and round the way your syllabus specifies; the chart's whole-number rows bracket the answer either way.
If your test has sections worth different points — say a 20-point multiple choice section and a 30-point essay — the equal-weight assumption breaks. Add the points earned across sections and divide by total points, or set the sections up as weighted rows in our weighted average calculator.
Frequently asked questions
How do I calculate a test grade from questions wrong?
Divide the number of correct answers by the total number of questions and multiply by 100. A 20-question test with 3 wrong is 17 ÷ 20 × 100 = 85%, a B on the standard scale.
What is an EZ Grader?
An EZ Grader is the sliding cardboard chart teachers have used for decades: set the number of test questions, and it shows the percentage score for each possible number of wrong answers. This page is the same tool in digital form — set the total once, then read scores straight off the chart while grading a stack of papers.
How many questions should a test have for clean percentages?
Totals that divide 100 evenly — 10, 20, 25, or 50 questions — produce whole-number percentages for every result. A 25-question test moves in steps of 4 points per question; a 30-question test produces repeating decimals like 96.7 and 93.3.
Can questions be worth different points?
This chart assumes every question is worth the same. For weighted sections, add up the points earned and points possible, then divide — or use our weighted average calculator with each section as a row.