Education
Square Root Curve Calculator
Apply the common square-root curve to a raw percentage or test score, then compare the raw grade, curved grade, letter estimate, and point increase.
Why do teachers use a square-root curve?
A square-root curve raises lower and middle scores more than scores already near 100%. That can be useful when an exam was too difficult but the teacher does not want to simply add the same number of points to everyone.
What formula does it use?
Curved % = √(raw % as a decimal) × 100
General form = (raw decimal)^exponent × 100
The calculator also includes a custom exponent option. An exponent closer to 1 gives a milder curve, while an exponent closer to 0.5 gives the classic square-root curve.
What mistake should students avoid?
Do not apply the curve twice. Also remember that square-root curves are usually unofficial unless your instructor clearly says this is the method being used.
Frequently asked questions
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It can be generous for low and mid scores, but high scores near 100 change much less.
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Some teachers use a curve that behaves like a square-root curve but is milder or stronger. The exponent lets you model that.
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With an exponent between 0 and 1, scores between 0 and 100 generally rise or stay the same.
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Enter 50 as points possible. The calculator converts it to a percentage before curving.
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No. A square-root curve transforms individual scores. A bell curve compares scores with the class distribution.