What Is an EZ Grader and How Do You Use It?
An EZ grader turns the number of wrong answers into a percentage and letter grade. See how it works, a grading chart, and a free EZ grader online.
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An EZ grader is a quick way to grade a test. You enter how many questions there were and how many the student got wrong, and it gives you the percentage and letter grade right away.
Teachers have used these for years, first as a little slide chart and now as a free online tool. This guide explains how an EZ grader works, shows a grading chart, and links to a free EZ Grader calculator you can use now.
What is an EZ grader?
An EZ grader is a tool that turns the number of wrong answers on a test into a percentage and a letter grade. Instead of working out the math for each paper, you just look up the score. It was built to make grading fast.
The original EZ grader was a small slide chart made of cardboard. A teacher would slide it to the number of questions on the test, then read off the percentage for each number of wrong answers. Today the same idea works online and on phones, with no chart to carry around.
The point has always been the same. Grade a stack of papers quickly, without doing the same sum over and over.
How an EZ grader works
Behind the tool is a simple formula. It finds the correct answers first, then turns them into a percentage.
Percentage = (Total questions − Wrong answers) ÷ Total questions × 100
Say a test has 40 questions and a student got 5 wrong. First, take away the wrong ones. 40 − 5 = 35 correct. Then divide by the total and multiply by 100. (35 ÷ 40) × 100 = 87.5%. After that, the percentage maps to a letter grade, so 87.5% is a B.
An EZ grader just does these steps for you the moment you type in the two numbers.
How to use an EZ grader
Using one takes only a few seconds. There are three small steps. Start by entering the total number of questions on the test. Then type in how many the student got wrong. The tool shows the percentage and the letter grade straight away, with no button to press and nothing to wait for.
From there you can grade the next paper by just changing the number wrong. The total questions stay the same for the whole class, so you only set that once. That is what makes grading a full stack so fast.
EZ grader chart

Here is a grading chart for a 20-question test. Each wrong answer takes off 5%. Find the number wrong and read across to the score and letter grade.
Wrong answers | Percentage | Letter grade |
|---|---|---|
0 | 100% | A |
1 | 95% | A |
2 | 90% | A |
3 | 85% | B |
4 | 80% | B |
5 | 75% | C |
6 | 70% | C |
7 | 65% | D |
8 | 60% | D |
9 | 55% | F |
10 | 50% | F |
For a different test size, the steps are the same, but each wrong answer is worth a different amount. On a 25-question test each one is 4%, and on a 50-question test each one is 2%. The calculator builds the full chart for any number of questions.
Set your own grading scale
Most EZ graders use the standard scale, where 90 and above is an A, the 80s are a B, and so on. That works for most classrooms. But not every school uses the same cutoffs.
Some schools start an A at 93%, or treat anything below 70% as failing. If your scale is different, you can still use the EZ grader. Just read the percentage it gives you and match it to your own letter grade cutoffs. The percentage does not change, only the letter you assign to it.
It helps to keep your school's grading scale nearby the first few times. After that you will know your cutoffs by heart.
Why teachers use an EZ grader
The main reason is time. A teacher with thirty papers does not want to work out thirty percentages by hand. With an EZ grader, the total questions are set once, and each paper takes a couple of seconds.
It also cuts down on mistakes. Doing the same sum over and over is exactly when a small slip creeps in, and one wrong percentage can mean a wrong letter grade. The tool gives the same correct answer every time.
For students, the same chart is handy too. After a test, you can check your own score before the teacher hands it back, just by counting how many you got wrong.
Use our free EZ grader
You do not need a cardboard slide chart anymore. Our free EZ Grader calculator lets you type the total questions and the number wrong, and it shows the percentage, the letter grade, and a full chart right away. There is no login and no cost.
If you would rather start from a score instead of wrong answers, the Grade Percentage calculator works that way, and the Letter Grade calculator turns any percentage into a letter. All free, no signup.
Conclusion
An EZ grader takes the slow part out of grading. Enter the total questions and the number wrong, and you have the percentage and letter grade in seconds.
It saves teachers time and helps students check their own scores. Try it yourself with the free EZ Grader calculator.