The final grade is a weighted average. For each assignment, the score percentage is multiplied by its weight. These weighted scores are summed up and then divided by the sum of the weights entered. Formula: Σ(Score % * Weight) / Σ(Weight).

You can enter the score as a percentage (e.g., "85") or as points earned out of total points (e.g., "42/50"). The calculator will convert points to a percentage automatically.

No, the weights do not necessarily need to add up to 100%. The calculator determines the final grade based on the relative weights you provide. If they don't add up to 100%, the result represents your grade based *only* on the assignments entered.

The letter grade is determined by comparing your final percentage grade against the minimum percentages defined in the 'Letter Grade Scale' section. You can adjust these thresholds to match your specific grading scale.