How a GPA calculator works (and why credit-weighting matters)
A GPA calculator turns letter grades into a single number on the US 4.0 scale, weighted by how heavy each course was. The right way — the way every US registrar does it — is to multiply each grade's points by the course's credit hours, sum those products (called quality points), then divide by the total credit hours. Most students start by averaging their letter-grade points and wonder why their official GPA looks different; the missing piece is the credit weighting.
The 4.0 grade scale at a glance
Standard US conversions used by this GPA calculator:
- A+ / A = 4.0 · A− = 3.7
- B+ = 3.3 · B = 3.0 · B− = 2.7
- C+ = 2.3 · C = 2.0 · C− = 1.7
- D+ = 1.3 · D = 1.0 · D− = 0.7
- F = 0.0
A handful of schools use a 4.3 scale where A+ is 4.3 and some high schools weight AP/Honors classes on a 5.0 scale. This calculator uses the most widely accepted 4.0 mapping; you can ignore the +/− if your school uses straight letter grades.
The formula in one line
GPA = Σ (grade points × credit hours) ÷ Σ (credit hours)
That's it. Every row in the table above is contributing one product to the numerator and one number to the denominator. The big result up top is the running ratio, recalculated the instant you change anything.
Computing a cumulative GPA
When you finish a semester you usually want your new cumulative GPA — across every course you've taken, not just the current term. Toggle "Include prior GPA" and enter your prior cumulative GPA and the credit hours behind it. The calculator multiplies the prior GPA by those credits to recover the prior quality points, adds in this term's products and credits, and divides. That's exactly how your school's transcript system does it.
Tips for boosting GPA realistically
Two pieces of math worth knowing. First, your GPA gets harder to move as more credits stack up — a single A at the start of college shifts GPA much more than the same A after 90 credits. Second, dropping a course before it counts (a withdraw, not an F) protects your GPA, while an F is essentially zero quality points. If you can repeat a course, many schools let the new grade replace the old in the GPA calculation — check your registrar.
Pair with the other math tools
Need to find what percentage a final exam contributes? Use the percentage calculator. Sharing a per-bill split? The percent off calculator handles discounts and tax. Curious about US tax rates? Try the federal income tax percentage calculator.