Test Grade Calculator — Score, Percentage & Letter Grade

How the test grade calculator works

A test grade is the share of the test you got right. The calculator subtracts the number wrong from the total, divides by the total and converts it to a letter using the standard U.S. scale. You can count either questions or points, and switch between entering how many you got wrong or how many you got right.

Test grade % = (Total − Wrong) ÷ Total × 100

Worked example

A 25-question chemistry quiz

You missed 3 of 25: (25 − 3) ÷ 25 × 100 = 88%, a B+.

One fewer wrong (2 missed) would give 92%, an A-.

How many can you miss? Common test lengths

The most questions you can get wrong and still earn each grade on the standard 90/80/70/60 cutoffs:

Questions	A (90%)	B (80%)	C (70%)	D (60%)
10 questions	1 wrong	2 wrong	3 wrong	4 wrong
15 questions	1 wrong	3 wrong	4 wrong	6 wrong
20 questions	2 wrong	4 wrong	6 wrong	8 wrong
25 questions	2 wrong	5 wrong	7 wrong	10 wrong
30 questions	3 wrong	6 wrong	9 wrong	12 wrong
40 questions	4 wrong	8 wrong	12 wrong	16 wrong
50 questions	5 wrong	10 wrong	15 wrong	20 wrong
100 questions	10 wrong	20 wrong	30 wrong	40 wrong

Want the whole list for one test? Every total from 3 to 100 has its own chart in our grade charts, or build a custom one with the EZ Grader.

How to calculate test grades

To calculate test grades by hand, subtract the number wrong from the total, divide by the total, and multiply by 100. That's exactly what this test calculator does, with the letter grade added. As a test score calculator it works with points too: enter the test's total points and the points you lost.

This calculator for test grades scores one paper at a time. Scoring a test for a whole class? The EZ Grader gives you every possible score at once.

Students: what your test grade means for your class

A single test rarely decides your grade by itself. If tests are 40% of your grade and you have four of them, one test is about 10% of your final grade. Plug your new score into the grade calculator with your other categories to see the real effect, or check what you'll need on the final with the final grade calculator.

Teachers: grading a stack of tests

If you're grading a class set, the EZ Grader is faster: enter the number of questions once and read every score off a printable chart. You can set your own school's cutoffs, like 93/85/77/70.

Frequently asked questions

How do I calculate my test score as a percentage?

Divide the number you got right by the total number of questions, then multiply by 100. Missing 3 on a 25-question test: (25 − 3) ÷ 25 × 100 = 88%.

How many questions can I miss and still get an A?

You can miss up to 10% of the questions for a 90% (A-). On a 20-question test that's 2, on a 25-question test it's 2, on a 30-question test it's 3, and on a 50-question test it's 5.

What if questions are worth different points?

Use points instead of questions. Enter the total points on the test and the points you lost. A 60-point test where you lost 7 points is 53 ÷ 60 = 88.3%.

Do teachers round test grades?

Many do, typically to the nearest whole percent, so 89.5% becomes 90%. Others truncate. This calculator shows up to two decimals so you can see exactly where you are.

How does one test affect my class grade?

That depends on how much the test category is weighted. Enter your test score along with your other grades in the grade calculator to see the effect on your overall grade.

Last reviewed October 28, 2026 by the GradeCalc team. See how we calculate.