EZ Grader Chart

How to Use the EZ Grader

The EZ grader above works from one number: enter how many questions the quiz has, and the chart lists every possible number wrong with its percent score and letter grade. At Chalkbox, we build free classroom tools, and this one runs in the browser with no account.

1. Enter the number of questions. "Number of questions" takes 1 to 200 and starts at 20.
2. Read the row for each number wrong. The chart runs from 0 wrong up to the number of questions. Each row shows the percent and a letter grade.
3. Use "Find a score" for one paper. Type a number wrong into the box, and that row is highlighted and scrolled into view.
4. Press "Print chart". The printout holds only the chart, its title and the number of questions, so a paper copy can sit beside the stack.

Every row comes from one formula: percent = (questions − number wrong) ÷ questions × 100, rounded to the nearest whole percent.

Take the starting setting of 20 questions. Each question is worth 5 points (100 ÷ 20 = 5), so every wrong answer drops the score by 5. One wrong is 95%, and 2 wrong is 90%.

Three options change what the chart shows:

• Show one decimal shows tenths of a percent instead of whole percents.
• Half points adds rows for 0.5, 1.5, 2.5 wrong and so on, for partial credit.
• Count by number correct switches the first column to the number correct. The percents stay the same.

Nothing you enter is saved or sent to a server. If you want to keep a chart for the next stack, press "Print chart" before you close the page.

How the EZ Grader Calculates Each Score

The EZ grader subtracts the number wrong from the number of questions, divides by the number of questions and multiplies by 100. In our internal check, we computed every row for 10, 20, 23, 25 and 50 questions with this formula and the rounding rule below.

A quiz with 23 questions shows why a chart helps. With 2 wrong, 21 ÷ 23 = 0.913..., so the chart shows 91%, an A. With 3 wrong, 20 ÷ 23 = 0.8696..., so the chart shows 87%, a B.

How Rounding Works

The EZ grader rounds to the nearest whole percent, and a half rounds up, so 89.5 becomes 90. Turn on "Show one decimal" to see tenths. With that view on, 23 questions and 2 wrong shows 91.3%.

Rounding can move a letter grade. On a 200-question test, 21 wrong gives 179 ÷ 200 = 0.895, which is exactly 89.5%. The default chart shows 90% and an A, while the one-decimal view shows 89.5%, which is a B on the 10-point scale.

If you never round a score up, use the one-decimal view. The letters on the chart then follow the unrounded score.

EZ Grader Chart for a 25-Question Quiz

A 25-question quiz gives each question 4 points (100 ÷ 25 = 4), so each wrong answer takes 4 points off. These rows match the EZ grader set to 25 questions.

Seven wrong means 18 correct out of 25, and 18 ÷ 25 = 0.72, or 72%, a C. The full chart keeps going past 8 wrong, all the way to 25 wrong, which is 0%.

Letter Grades on the EZ Grader Chart

The EZ grader assigns each letter from the rounded percent shown, using the common 10-point scale:

• A: 90 to 100
• B: 80 to 89
• C: 70 to 79
• D: 60 to 69
• F: below 60

Schools and districts use different scales and plus/minus cutoffs, so treat the letters on the chart as a guide. If your district uses another scale, read the percent column and apply your district's cutoffs to it. The percent comes from the formula alone, so it is correct under any scale.

The letter follows the rounded percent, so a score that rounds up to 90 prints an A. The 200-question example above is one case: 89.5% rounds to 90%. If your district grades from the unrounded score, turn on "Show one decimal" before you copy letters into a gradebook.

Half Points and Partial Credit

The "Half points" option adds a row between each pair of whole numbers wrong, so a paper with partial credit has its own row. With half points on, the first column reads 0, 0.5, 1, 1.5, 2, 2.5 and so on.

Take a 40-question test where a student misses 4 questions and earns half credit on a fifth. Count that as 4.5 wrong. The chart works it out as 35.5 ÷ 40 = 0.8875 and shows 89%, a B, or 88.8% with one decimal.

To use half points across a stack, count each half-credit answer as half a wrong answer. Add the whole and half misses for each paper, then read that total in the chart.

Counting by Number Correct

"Count by number correct" switches the first column to the number correct, and every percent stays the same. Use it if you mark the answers a student got right instead of the ones they missed.

On a 25-question quiz, 18 correct shows 72%, the same score as 7 wrong. The "Find a score" box takes a number correct in this view, so you can type 18 and jump to that row.

When Points Math Fits Better Than a Number-Wrong Chart

A number-wrong chart gives the right percent only when every question is worth the same. If questions carry different points, such as a 5-point essay plus 1-point multiple-choice questions, use points earned ÷ points possible instead.

A quiz with 20 one-point questions and a 5-point essay has 25 points possible. A student who gets all 20 multiple-choice questions right and 0 on the essay earns 20 ÷ 25 = 80%.

A chart set to 21 questions counts that essay as one wrong answer: 20 ÷ 21 = 0.952..., or 95%. That is 15 points too high from a single question.

The grade calculator for teachers guide covers points math, weighted grades and curves. Use it for any test that mixes point values, and keep the EZ grader for quizzes and tests where every question counts once.

What the EZ Grader Does Not Do

The EZ grader builds one chart for equal-weight questions, and it does not weight questions, curve scores, keep a gradebook or save your work. Each gap has a simple fix:

• Weighted questions. Divide points earned by points possible, as in the essay example above.
• Curves. The chart shows raw percents only. The grade calculator guide linked in the section above covers curves.
• Gradebook. Copy each percent into your own gradebook as you finish each paper.
• Saving. Nothing is stored, so press "Print chart" to keep a copy for the next stack with the same number of questions.
• Other letter scales. The letters use the 10-point scale, so apply your district's cutoffs to the percent column.

Chalkbox Tools for Writing the Quiz and Reporting Grades

Chalkbox has free generators for the work before and after grading. To write the questions, use the quiz generator, the test generator or the multiple choice generator. If every question on the finished quiz is worth 1 point, the EZ grader chart fits it with no changes.

For quick checks at the end of a lesson, the exit ticket generator builds the questions. When grades go home, the report card comment generator drafts comments to go with them.

For quizzes and tests where every question is worth the same, the EZ grader gives the exact rounded percent for each number wrong, so you skip the division on every paper. When question weights differ, switch to points earned ÷ points possible. If your district's scale differs from the 10-point scale, apply your own cutoffs, and turn on one decimal if you never round up. To start, type the number of questions into the EZ grader above, press "Print chart" and grade the stack with the paper copy beside you.