Your grade point average, weighted by credit hours.
Standard 4.0 scale: 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, F=0. Each course’s points are weighted by its credit hours, so a 4-credit A lifts more than a 1-credit A. (Scales vary by school — some use A+=4.3 or straight A=4/B=3 with no pluses; check yours if the number looks off.)
How is GPA weighted? Multiply each course’s grade points by its credits, add them all, divide by total credits. A grade in a high-credit course moves the average more.
Can one F ruin my GPA? It hurts most early, when total credits are few. The same F is diluted as more credits accumulate — the calculator lets you model recovery.