Grading Calculator

Practical guide

Letter Grade Scales Explained: 10-Point and Plus/Minus

See how a common 10-point letter grade scale and a plus/minus scale work, why schools differ, and how rounding affects a cutoff such as 89.5.

By Grading Calculator

A common 10-point scale

Many U.S. classrooms use a 10-point scale, in which each letter covers ten percentage points. A common version looks like this, but your school or district may set different cutoffs.

On this scale an 89% is a B, and a 90% is an A, so a single point can change the letter.

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

A common plus/minus version

Some schools split each letter into thirds. One common way is a minus for the lowest three points, a plus for the highest three, and a plain letter in between. For example, 90% to 92% is an A−, 93% to 96% is an A, and 97% and above is an A+. Other schools do not give an A+ at all, and some use only pluses and minuses for B and C.

The grading chart on this site has an editable letter scale, so you can enter the cutoffs your class uses.

Why scales differ

No single scale applies everywhere. The College Board BigFuture page on GPA lists a table in which D is 66 to 69 and anything below 65 is an F, and it notes that schools vary in their cutoffs and in how they use pluses and minuses. That table is not the same as the 10-point scale above, where D starts at 60.

Colleges differ too. The University of North Carolina registrar lists grade points for A, A−, B+, B, B−, C+, C, C−, D+, D and F, which shows a plus/minus system tied to grade points rather than to one fixed percent table. Whichever scale you use, read the syllabus or the district grading policy.

Rounding and the 89.5 question

Cutoffs and rounding interact. If a class rounds to the nearest whole number, 89.5% rounds up to 90% and earns an A. If the class does not round, 89.5% is still below 90% and stays a B.

Ask which rule applies before you plan around a borderline score, and apply the same rule to every student.

  • Check whether rounding happens on each assignment or only on the final average.
  • Check whether the cutoff is written as 90% or as 89.5%.
  • Use the scale printed in the syllabus, not one from another school.

Sources and further reading

Put the idea to use with our Grading chart and test score calculator.

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