This calculator helps you assign letter grades based on a normal distribution curve, ensuring a balanced and statistically fair spread of results across a class. It’s designed for educators and institutions that use relative grading rather than absolute score thresholds.
By entering the total number of students, the highest score, and the lowest score, the calculator determines the full score range and divides it into grade intervals (A–F).
Grades are allocated according to the standard normal distribution model:
A = 2%, B = 14%, C = 68%, D = 14%, F = 2%.
This approach assumes that most students achieve around the average score (Grade C), with fewer students earning very high (A) or very low (F) marks — similar to a bell-shaped curve.
The results display the number of students and score range for each grade category, helping visualize the performance spread across the class. It’s a quick, transparent way to model curved grading and maintain fairness across varying levels of exam difficulty.