Two students with the same grades can have different GPAs depending on which scale their school uses. Here's why.
An unweighted GPA uses a standard 0–4.0 scale where every class counts the same — an A in gym and an A in AP Calculus are both worth 4.0.
A weighted GPA adds extra points for harder classes — typically +0.5 for Honors and +1.0 for AP or IB — before averaging. This means the scale can go above 4.0, often up to 5.0, and an A in AP Calculus (5.0) would outweigh an A in a regular class (4.0).
Which one matters for college? Both, usually. Many colleges recalculate every applicant's GPA on their own unweighted scale for fair comparison, but they also look at your transcript to see how many advanced classes you took — which is exactly what the weighted GPA is meant to reflect.