GPA Explained: How Weighted and Unweighted GPA Actually Work
GPA looks like a single number, but the formula behind it — and which version a school uses — changes what that number actually means.
The basic GPA formula
GPA is a credit-weighted average of your grade points. Each letter grade converts to a point value (commonly A = 4.0, B = 3.0, C = 2.0, and so on), and each class's grade points are multiplied by its credit hours before everything is averaged together. A 4-credit class counts more toward your GPA than a 1-credit class with the same letter grade — this is why two students with the same letter grades but different credit loads can end up with different GPAs. The GPA Calculator handles this weighting automatically once you enter grades and credit hours.
Unweighted GPA: every class capped at the same scale
Unweighted GPA treats every class the same regardless of difficulty — an A in an elective and an A in an advanced placement class both count as 4.0. This is the simpler, more common version, typically capped at 4.0.
Weighted GPA: harder classes count for more
Weighted GPA gives extra points for honors, AP, or IB-level classes — often adding 0.5 to 1.0 extra point for an A in those courses, which is why weighted GPAs can exceed 4.0 (a 4.3 or 5.0 weighted GPA is common in schools that use this system). The core idea is to reward students for taking harder classes rather than penalizing them relative to someone who took easier ones and got the same letter grade. Not all schools weight GPA the same way, so a weighted GPA from one school isn't always directly comparable to one from another.
Why one bad grade can hit harder than expected
Because GPA is a credit-weighted average, a single low grade in a high-credit class pulls the overall average down more than the same low grade in a 1-credit class would. This is also why GPA tends to be "sticky" over time — as more credits accumulate, each new semester's grades have proportionally less power to move the overall number, for better or worse.
Figuring out what you need going forward
If you're trying to hit a specific final grade in a single class rather than your overall GPA, that's a slightly different calculation involving assignment weights rather than credit hours — the Weighted Grade Calculator is built for that specific question, including working out what you'd need on a remaining assignment to hit a target grade.