Grade a whole stack of tests by counting what's wrong.

The EZ Grader is the teacher's shortcut: set how many questions the test has, count the wrong answers on each paper, and read off the percentage and letter grade — no division, no calculator, paper after paper.

✓The classic slide-chart, rebuilt. The full grading chart for your test length, generated instantly.
✓Any test length. From a 5-question exit ticket to a 100-question final.
✓Nothing leaves your device. Scores are computed in your browser, never uploaded.

EZ Grader

—

Score

–

Correct

Set the test length and count the wrong answers.

Total questions Wrong answers

Test length

Use +/− letter grades

Grading chart · 20 questions

Tap any row to look it up

Wrong	Correct	Score	Grade

Getting started

How to use the EZ Grader

Set the test length

Enter the number of questions, or tap a preset. The whole chart rebuilds for that length — a 20-question quiz and a 50-question test grade very differently.

Mark the paper

Go through the student's test and count the misses. Blanks count as wrong — they earn no points either way.

Enter the wrong count

Type it in, or find it in the chart below. The percentage and letter grade appear instantly, color-coded by band.

Repeat for the stack

The test length stays put, so each new paper is just a new wrong count. Grade the whole class without touching a calculator.

See the math

Why test length changes everything

An EZ grader is only ever doing one division — but the value of each question depends entirely on how many questions there are. The same three wrong answers earn an A on a 50-question test but only a C− on a 10-question quiz:

Same 3 wrong answers on…	Correct	Score	Grade
a 10-question quiz	7 / 10	70.0%	C−
a 20-question quiz	17 / 20	85.0%	B
a 25-question test	22 / 25	88.0%	B+
a 50-question test	47 / 50	94.0%	A
Each wrong answer costs 100 ÷ questions points

On a 10-question quiz every miss costs 10 points, so two slips can drop a student a full letter band. On a 100-question final each miss costs a single point. That's why the chart has to be rebuilt for every test length — and why short quizzes feel so unforgiving.

The EZ grader formula

Score % = (Total − Wrong) ÷ Total × 100

Subtract the wrong answers from the total questions to get the number correct, divide by the total, and multiply by 100. A 40-question test with 6 wrong: (40 − 6) ÷ 40 × 100 = 85% — a B.

Equivalently, each question is worth 100 ÷ Total points, so the score is 100 minus the wrong count times that value. The chart simply pre-computes every row of that arithmetic for you.

The concepts

Grading by wrong answers, done right

Counting errors instead of points feels backwards the first time, but it's the fastest reliable way to grade equal-weight tests — as long as you know where the method's edges are.

Every question counts the same

The chart assumes each question is worth one equal slice of the grade. That's true for most quizzes and multiple-choice tests. The moment questions carry different point values — a 10-point essay beside 2-point multiple choice — switch to counting points, not wrong answers.

The slide chart teachers grew up with

The original EZ Grader is a cardboard slide chart: set the number of questions in the window and the percentages line up against the wrong counts. This page is the same idea with the arithmetic done for you — and letters and plus/minus bands the cardboard version never had room for.

Rounding is a policy, not a detail

A score of 89.6% sits between B+ and A−. This chart grades on the exact percentage, so 89.6% reads as a B+. If your school rounds .5 and up, bump borderline papers yourself — and apply the same rule to every student, every time.

Reference

The letter scale behind the chart

The chart converts percentages to letters on the standard US scale below. Turn off Use +/− letter grades in the grader and it falls back to the five whole-letter bands — A at 90, B at 80, C at 70, D at 60, F below.

Letter	Percentage	GPA	What it means
A+	97–100%	4.0	Exceptional
A	93–96%	4.0	Excellent
A−	90–92%	3.7	Excellent
B+	87–89%	3.3	Above average
B	83–86%	3.0	Good
B−	80–82%	2.7	Good
C+	77–79%	2.3	Average
C	73–76%	2.0	Average
C−	70–72%	1.7	Below average
D+	67–69%	1.3	Poor
D	63–66%	1.0	Poor
D−	60–62%	0.7	Minimum pass
F	Below 60%	0.0	Failing

Watch out

Common EZ grading mistakes

Reading the wrong chart.

A chart set for 25 questions grades a 20-question quiz wrong on every single row. Check the test length before the first paper, not after the last one.

Skipping the blanks.

Unanswered questions earn no points, so they belong in the wrong count. Leaving them out quietly inflates grades for students who ran out of time.

Using it on uneven point values.

If question 12 is worth 10 points and the rest are worth 2, a wrong count treats them as equals. Grade that test by points instead.

Rounding one student's paper and not the next.

Borderline percentages come up in every stack. Pick a rounding rule before you start grading and hold it for the whole class.

Forgetting the answer key changed.

If you threw out a flawed question after the test, reduce the total questions by one — otherwise every student is graded against a question nobody could get right.

Answers

Frequently asked questions

How does an EZ grader work?

An EZ grader is a grading chart keyed to the number of questions on a test. You set the test length once, then read down the chart: each row shows how many answers were wrong, the percentage that leaves, and the letter grade. It replaces doing the same division over and over for every paper in the stack.

How do I calculate a grade from wrong answers?

Subtract the wrong answers from the total questions to get the number correct, divide by the total, and multiply by 100. On a 25-question quiz with 3 wrong, that's (25 − 3) ÷ 25 × 100 = 88%, a B+ on the standard scale. The grader at the top of this page does it as you type.

What is 7 wrong out of 50?

7 wrong out of 50 means 43 correct, which is 86% — a B on the standard grading scale. Each question on a 50-question test is worth exactly 2 percentage points, which is why even-numbered scores dominate that chart.

Does the EZ grader handle plus and minus grades?

Yes. Leave the plus/minus toggle on and the chart letters use the full scale — A+, A, A−, B+, and so on. Turn it off and the chart uses whole letters only (A, B, C, D, F), the way many elementary and middle schools grade.

How many questions can the chart handle?

Any test from 1 to 200 questions. Short quizzes, unit tests and 100-question finals all work — the chart rebuilds itself for whatever length you enter, and the preset buttons cover the most common lengths.

Should unanswered questions count as wrong?

In almost every classroom, yes — a blank answer earns no points, so it counts the same as a wrong one. Add blanks into your wrong count before reading the chart. The exception is a test with a guessing penalty, where blanks and wrong answers are scored differently.

What about partial credit?

The chart assumes every question is worth the same and is either right or wrong. If you award half credit, count two half-credit answers as one wrong. For heavily weighted or partial-credit work, the points grade calculator is the more accurate tool.

Is this EZ grader free?

Completely. No account, no install, and nothing is uploaded — the chart is generated in your browser, so student scores never leave your device.

Keep going

More grade tools for your classroom

The EZ Grader handles equal-weight tests. When the grading gets more complicated — weights, points, curves, a whole semester of courses — these tools take over.