Calculate your Grade 12 School-Based Assessment (SBA) mark quickly and accurately. This free SBA Calculator helps South African learners determine their current SBA percentage based on tests, assignments, projects, practical tasks, and examinations completed throughout the year. What is SBA? A School-Based Assessment (SBA) mark is the score you earn from tests, assignments, projects, practical tasks, and exams completed during the school year. These marks contribute towards your final Grade 12 subject result and play an important role in your overall NSC performance.