A grading scale is the table that turns a percentage into a letter grade. The three most common US scales are the 10-point scale, the plus/minus scale and the 7-point scale, and the same score can earn a different letter on each. A 92%, for example, is an A on the 10-point scale, an A− on the plus/minus scale and a B on the 7-point scale.

This guide shows the full chart for every scale, with GPA points, so you can see exactly where each cutoff sits. If you already have a percentage and just want the letter, the letter grade calculator converts it on any of the three scales in one step.

What is a grading scale?

A grading scale is a list of percentage ranges, each linked to a letter grade. When you finish a test or a course, you first work out a percentage. The scale then tells you which letter that percentage earns. The percentage comes from a calculation, while the scale is a rule that someone chose.

That is the key point: a scale is a decision, not a law of maths. A school can move the A cutoff from 90% to 93% and change the letters of hundreds of students without changing a single score. This is why two students with the same percentage can end up with different grades, and why you should always find out which scale applies before you compare results.

The 10-point grading scale

The 10-point scale, sometimes called the standard or uniform scale, is the one most people picture. Each letter covers a band of ten percentage points, and F covers everything below 60%. It is very common in US schools because it is easy to explain: 90s are As, 80s are Bs, and so on.

On this scale a score of exactly 90% is an A and 89.9% is a B, so the boundary matters. If your score is that close, see how your teacher handles rounding. The scale itself has no letter between B and A, so there is no “B+” or “A−”.

The plus/minus grading scale

The plus/minus scale splits each letter from A to D into three levels. A student with an 88% gets a B+, and a student with an 81% gets a B−. This gives a more detailed picture, and it is the scale many colleges and universities use.

Schools differ on the details. Some do not use an A+ at all, so 97% and 93% are both an A. Some give an A+ a higher value of 4.3 grade points. Some do not use a D−. Treat the chart above as the most common version and confirm the exact numbers in your handbook or syllabus.

One effect worth knowing is that plus/minus can lower a GPA compared with the 10-point scale. A 90% is an A (4.0) on the 10-point scale but an A− (3.7) on the plus/minus scale. At the same time it can raise it: an 89% is a B (3.0) on the 10-point scale but a B+ (3.3) here.

The 7-point grading scale

The 7-point scale makes each letter a little harder to earn. An A starts at 93%, a B at 85%, a C at 77% and a D at 70%, and anything below 70% is an F. Some school districts use it, often with a plain A to F system and no plus or minus.

The biggest difference from the 10-point scale is the pass line. On the 10-point scale a 65% is a D. On the 7-point scale the same 65% is an F, because the lowest passing grade is 70%. If you move schools, or compare yourself with a friend, this is the difference that surprises people most.

Same score, three scales

This table puts the three scales side by side. Each cell shows the letter and the GPA points for that score:

Look at 92%: it is an A on the 10-point scale, an A− on the plus/minus scale and a B on the 7-point scale. Look at 74% too. It is a C on the first two scales and a D on the 7-point scale. A few percentage points can change a letter, and the scale decides which few.

How to convert a percentage to a letter grade

1. Get the exact percentage. Use the full decimal, such as 87.6%, and do not round yet.
2. Choose the scale. Use the one in your syllabus or handbook.
3. Find the band. Look for the highest cutoff that is less than or equal to your percentage.
4. Read the letter and the grade points. Write both down if you need the GPA later.

Here is a worked example. A student finishes a course with 87.6%. On the plus/minus scale the 87% cutoff is the highest one at or below 87.6, so the grade is a B+ (3.3 grade points). On the 10-point scale the highest cutoff at or below 87.6 is 80, so the grade is a B (3.0). On the 7-point scale it is 85, so the grade is again a B (3.0). The same course result produces two different GPA values, which is why it matters to know the scale before you work out a GPA.

Grading scales and GPA

Every letter on a scale is linked to grade points, and GPA is built from those points. On the 10-point and 7-point scales, A is 4.0, B is 3.0, C is 2.0, D is 1.0 and F is 0.0. The plus/minus scale adds the steps in between, such as 3.7 for an A− and 3.3 for a B+.

To find a GPA, you multiply each course’s grade points by its credit hours, add the results, and divide by the total credit hours. For example, an A (4.0) in a 3-credit course and a B (3.0) in a 4-credit course give (4.0 × 3 + 3.0 × 4) ÷ 7 = 24 ÷ 7 = 3.43. Our guide explains how GPA points work in detail, and the GPA calculator does the arithmetic for a whole semester.

Some schools also add a bonus point for honors, AP or IB courses, which is called a weighted GPA. That is separate from the grading scale: the scale gives the letter, and the school’s GPA rules turn the letter into points.

Which scale does your school use?

There is no national rule, but there are common patterns. The table shows where each scale tends to appear. Treat it as a guide, not a guarantee.

To find out for certain, look in these places, in this order:

1. The course syllabus, which often has a grading table.
2. The student handbook or the school’s website.
3. The online gradebook, which sometimes shows the scale.
4. Your teacher or school office, if none of the above says.

Remember that the scale can change from course to course. An individual instructor at a college may use a different scale from the rest of the department.

Why schools use different scales

Each scale has a reason behind it. The 10-point scale is simple, so families can understand a report card at a glance. The plus/minus scale separates a 90 from a 96, which can matter for scholarships and class rank. The 7-point scale makes each letter harder to reach, and districts that adopted it usually wanted higher standards for an A.

The scale is only the last step, though. Before you apply it, the percentage has to be built from scores, points and weights, which is covered in our guide on how schools calculate grades. In some classes the grade does not start as a percentage at all, but as a rubric score, and our comparison of rubric vs percentage grading shows how the two relate. For teachers who need to pick a scale and explain it clearly, we have collected some teacher grading tips.

Other grading systems

This guide covers the common US scales. Many countries and institutions use something different, and the same ideas apply: a rule that turns marks into a label.

• UK universities usually classify degrees as First, 2:1, 2:2 and Third, based on average marks.
• Many European universities use ECTS grades, which are written as letters from A to E for passes.
• In India and Pakistan, many boards and universities use percentage divisions or a CGPA scale instead of letters.

These systems vary by institution, so the rules in your own school’s documents always come first.

Common mistakes with grading scales

• Assuming every school uses the 10-point scale. Check before you compare.
• Comparing GPAs from different scales. A 3.5 on one scale is not the same achievement as a 3.5 on another.
• Forgetting the plus/minus steps. A B+ and a B− are both a B, but they carry different grade points.
• Using the wrong pass line. A 65% passes on the 10-point scale and fails on the 7-point scale.
• Treating a letter as an exact number. A B on the 10-point scale can be anything from 80% to 89.99%.

Frequently asked questions

What is the most common grading scale?

The 10-point scale is the one most people know and is very common in US schools. Many colleges use a plus/minus version of it instead.

Is 90% an A?

On the 10-point scale, yes. On the plus/minus scale it is an A−, and on the 7-point scale it is a B.

What is the difference between the plus/minus scale and the 10-point scale?

The plus/minus scale splits each letter into three levels, such as B+, B and B−, and gives each level its own grade points. The 10-point scale has one level per letter.

What is the lowest passing grade?

It depends on the scale and the school. On the 10-point scale a D starts at 60%. On the 7-point scale it starts at 70%. Some schools do not count a D as passing for certain courses.

Is the 7-point scale harder?

Yes. Each letter needs a higher percentage than on the 10-point scale, so the same score often earns a lower letter.

How do I convert a percentage to a letter grade?

Find your score in your school’s scale and read the letter next to it. Or enter the percentage in the letter grade calculator and pick the scale.