How to Calculate GPA

Every GPA calculation is the same two lines, whatever the school calls it:

"Quality points" is the registrar's term for the first line. You will see it on a transcript, usually in a column next to your credits. It is the only part of the calculation that does any real work — once you have quality points, a GPA is just a division.

1. List every course with its letter grade and its credit hours. Credits are on your transcript or in the course catalog.
2. Convert each letter to grade points using your school's scale. The common one is below.
3. Multiply grade points by credit hours for each course.
4. Add up those products, and separately add up the credit hours.
5. Divide the first total by the second.

The step people skip is the third one. Averaging the grade points directly — adding 4.0 + 3.3 + 3.7 and dividing by three — silently treats a 1-credit lab as equal to a 4-credit lecture, and gives an answer that looks reasonable and is wrong.

The most common US scale, and the default in the calculators here:

This is common, not universal. Plenty of schools use whole letters only, where a B+ and a B are both 3.0. Some award 4.3 for an A+; many cap the scale at 4.0 so an A+ and an A are worth the same. The percentage ranges vary more than the points do.

One semester, five courses, fourteen credit hours:

48.3 ÷ 14 = 3.45.

Now average the five grade points directly instead: (4.0 + 3.3 + 3.7 + 3.0 + 2.3) ÷ 5 = 3.26. That is nearly two tenths lower, and it is wrong — it gives the 1-credit lab the same say as the 4-credit biology course. The weighting is the whole point.

A 4-credit course counts four times as much as a 1-credit one. That sounds obvious written down, but it is what makes a GPA hard to predict: the grade that matters most is not your best or your worst, it is the one attached to the most credits.

In the example above, swapping the lab's C+ for an A moves the GPA from 3.45 to 3.57 — a gain of 0.12 for one letter. Swapping the biology A for a C+ instead drops it to 2.96, a loss of 0.49 from the same size of change. Same scale, four times the weight.

The practical version: when you are deciding where to put your remaining effort, put it into the heaviest course, not the one closest to a grade boundary.

• Averaging grade points instead of weighting them. The single most common error, and the reason a hand-calculated GPA usually comes out slightly wrong.
• Leaving out failed courses. An F contributes 0 points but its credits still count in the denominator. Dropping the row entirely inflates the result.
• Counting pass/fail or transfer credits. These usually carry credit but no grade points, so they belong in neither half of the fraction.
• Using percentages as grade points. An 87% is not 8.7 points; convert to a letter first, then to points.
• Assuming plus and minus grades exist. If your school uses whole letters, a B+ is 3.0 and using 3.3 overstates your GPA on every such course.
• Rounding early. Round once, at the end. Rounding each course's quality points first accumulates error across a full transcript.

Every one of these is set by the institution, not by any national standard:

• Whether plus and minus grades carry distinct point values.
• Whether an A+ is 4.0 or 4.3.
• Which courses are excluded from the GPA — remedial, pass/fail, transfer, audited.
• What happens when you repeat a course: both grades counted, or the first replaced.
• Whether the GPA is truncated or rounded, and to how many decimal places.

So two accurate GPAs for the same student at two schools can differ noticeably. If the number matters — a scholarship threshold, an honors cutoff, a program requirement — the figure on your transcript is the one that counts, not the one you worked out.