GPA Calculator: 4.0 and 4.3 Scales with Plus/Minus Grades

GPA Calculator

A GPA calculator turns letter grades and credit hours into a grade-point average (GPA). A GPA is one number, usually between 0 and 4.0, that summarizes performance across many courses. Each grade is converted to a point value, weighted by the course's credit hours, and averaged.

What the calculator does

Each course gets its own row with an optional name, a letter grade, and its credit hours. The calculator converts every grade to points on the selected scale and reports four figures: the term GPA, the cumulative GPA, total credits, and total quality points. A per-course table shows the quality points behind each row.

A row is counted only when it has both a selected grade and more than zero credits. Blank or partly filled rows are simply left out, so unused rows do no harm. Entering a prior GPA and the number of credits it covers adds a cumulative GPA that combines the old record with the new courses.

How to calculate GPA

The calculator uses the standard registrar definition, as described by the Penn State Office of the University Registrar in "Calculating Your Grade-Point Average":

$G = \frac{Q}{C}$

where $G$ is the grade-point average, $Q$ the total quality points and $C$ the total credits.

Quality points for one course are the grade's point value multiplied by the course's credit hours. An A (4.0) in a 3-credit course is worth 12.0 quality points. Written out for a full term:

$G = \frac{\sum_i g_i c_i}{\sum_i c_i}$

where $g_i$ is the point value of the grade in course $i$, $c_i$ is that course's credit hours, and the sums run over every counted course. Credits act as weights. A 4-credit course moves the average more than a 1-credit course with the same grade. The calculator keeps full precision internally and rounds only the displayed result, to two decimal places.

Grading scales

The same letter grade is worth different points at different schools, so the scale is an explicit choice. Three scales are offered:

The plus/minus column follows the College Board conversion table ("How to Convert Your GPA to a 4.0 Scale"): each plus or minus step changes the value by 0.3, and A+ is capped at 4.0. The 4.3 column is the same table except that A+ is worth 4.3, as in the Stanford University registrar's grading system.

Switching scales keeps every grade the new scale also defines. A grade the new scale lacks loses its plus or minus sign, so a B+ becomes a B on the simple scale. A grade is never valued on a scale that does not define it.

Worked example

Four courses on the 4.0 plus/minus scale:

Total credits: 14. Total quality points: 14.80 + 9.90 + 12.00 + 12.00 = 48.70. The term average is then 48.70 ÷ 14 = 3.4786, shown as 3.48.

On the simple 4.0 scale, an A in 3 credits, a B in 4 credits, and a C in 3 credits give (12 + 12 + 6) ÷ 10 = 3.00.

Cumulative GPA

A cumulative GPA combines an existing record with the new courses. The prior quality points are rebuilt by multiplying the prior GPA by the credits it covers:

$G_c = \frac{G_p C_p + Q}{C_p + C}$

where $G_c$ is the cumulative average, $G_p$ the prior GPA, $C_p$ the credits that prior GPA covers, and $Q$ and $C$ the new quality points and new credits from above.

Continuing the example, a prior GPA of 3.20 over 30 credits represents 3.20 × 30 = 96 quality points. Combined with the term above, that is (96 + 48.70) ÷ (30 + 14) = 144.70 ÷ 44 = 3.2886, shown as 3.29.

Both prior fields must be filled in. With only one of them, the cumulative line stays blank rather than guessing the other value. If the prior GPA was earned on a different scale, the combined figure is an approximation.

Conventions and limits

Grading policies differ between schools, so the calculator states its choices instead of hiding them.

• A+ value. Some schools cap A+ at 4.0, some use 4.3, and some use 4.33 with steps of 0.33 instead of 0.3. The calculator offers the 4.0 and 4.3 conventions; a school on the 4.33 system will get a slightly different number.
• Rounding. Results are rounded to two decimals for display. Some registrars truncate instead, so 3.4786 would appear there as 3.47, not 3.48.
• Excluded courses. Pass/fail, withdrawn, and incomplete courses carry no grade points at most schools. They should be left out of the list. Rows with zero credits are not counted.
• Input bounds, enforced in the calculation itself. Credits per course must be between 0 and 20, and prior credits between 0 and 10,000; values outside those ranges produce an error, not a clamped guess. The prior GPA must be between 0 and the selected scale's maximum (4.0, or 4.3 on the 4.3 scale). At most 60 course rows are accepted; a longer list is refused whole rather than partly averaged. A bad prior GPA or prior credits value blocks only the cumulative line, because the term GPA never depended on those fields.

Frequently asked questions

How is GPA calculated? Multiply each grade's point value by the course's credit hours to get quality points, add them up, and divide by the total credit hours. An A− (3.7) in a 4-credit course contributes 14.8 quality points and 4 credits to that division.

What is a quality point? One course's contribution to the GPA: its grade value times its credit hours. Registrars sum quality points and divide by credits, which is exactly what this calculator does.

Is an A+ worth 4.0 or 4.3? It depends on the school. The College Board conversion caps A+ at 4.0, while some universities, such as Stanford, count it as 4.3. The calculator has a scale option for each; pick the one that matches the school's policy.

Do pass/fail classes count toward GPA? At most schools, no. A passed pass/fail course earns credits but no grade points, so it does not change the GPA. Leave such courses out of the list.

Why did the GPA change after switching scales? The same letters are worth different points. A B+ counts as 3.3 on the plus/minus scales but becomes a plain B worth 3 on the simple scale, so the average shifts.

Can credit hours be fractions? Yes. Half-credit and quarter-credit courses are accepted; any credit value from 0 to 20 works, and the credits field steps in increments of 0.25.