Letter Grade Scale

There is no single official letter grade scale. Two versions cover most US classrooms: the plus/minus scale (an A starts at 93, with A− and B+ bands between the plain letters) and the plain 10-point scale (an A starts at 90, no bands). This site's calculators use the plus/minus scale; both are listed here in full.

The plus/minus scale

Letter	Percentage	GPA points (4.0 scale)
A+	97–100	4.0
A	93–96	4.0
A−	90–92	3.7
B+	87–89	3.3
B	83–86	3.0
B−	80–82	2.7
C+	77–79	2.3
C	73–76	2.0
C−	70–72	1.7
D+	67–69	1.3
D	63–66	1.0
D−	60–62	0.7
F	Below 60	0.0

The plain 10-point scale

Letter	Percentage	GPA points (4.0 scale)
A	90–100	4.0
B	80–89	3.0
C	70–79	2.0
D	60–69	1.0
F	Below 60	0.0

These scales are conventions, not laws. Some schools start an A at 92 or 94, some weight honours and AP courses above 4.0, some do not use D−, and many teachers round borderline percentages by their own policy. Your syllabus and student handbook override anything on this page.

Frequently asked questions

Is 90 an A or an A−?

Both, depending on the scale: a plain-scale school calls 90 an A; a plus/minus school calls it an A−. This is the single most common scale difference, and it is why the calculators here let you type any target percentage instead of picking a letter.

Why is an A+ worth the same 4.0 as an A?

On the standard 4.0 scale the top is capped, so A+ and A both convert to 4.0 — the + shows on the transcript but not in the GPA. A few schools use a 4.3 scale where an A+ counts for more; check yours.

What letter is a 75%?

On both scales above, a C: 73–76 is a C on the plus/minus scale, and 70–79 is a C on the plain scale. A 75 is safely mid-C either way — the scales mostly disagree at the boundaries.

How do letter grades become a GPA?

Each course's letter converts to points from the tables above, then those points are averaged (usually weighted by credit hours). That roll-up is a GPA calculation, a step beyond a single course grade.