Square Root Curve Calculator & Grading Chart
Apply the standard √Score × 10 square root curve formula to single scores, class batches, or reference the full lookup chart below.
Tired of manually adjusting grades?
AssignClear tracks assignment progress, missing work recovery, and grade adjustments automatically for your whole class.
How Does the Square Root Curve Formula Work?
The square root curve is one of the most widely accepted grading adjustments in middle school, high school, and university STEM courses. The mathematical formula is:
Because square root functions are concave, the curve delivers a progressively decreasing benefit as the raw score increases. A failing grade of 49% jumps by +21 points to 70% (C-), while an above-average grade of 81% gains +9 points to 90% (A-).
Rescues borderline failing scores without artificially inflating grades to an unearned A.
Shifts the true median of a rigorous exam into a solid B range.
A perfect 100% remains exactly 100%, avoiding score overflow above maximum.
Explore Other Grade Curve Tools
Frequently Asked Questions
Is the square root curve fair to high-achieving students?
Yes, because it never reverses the rank order of students. If Student A scored higher than Student B on the raw exam, Student A will always have a higher curved score.
Can I use this curve if raw test scores are out of 50 or 75?
Yes. First convert the raw points to a percentage (e.g., 38 out of 50 = 76%), and then apply the square root formula.