Square Root Curve Calculator
A square root, or Texas curve is a quick and easy way to help all students, but help the lower scores a little more
A square root curve, or Texas curve, is designed to be easy to use and has the advantage of helping the lower scores more than the higher scores — if that's an advantage to you. It's also dead simple to do.
Let's look at a couple of examples. Jimmy gets a raw score of 75% on a test.
\[\begin{align} Score &= 10 \times \sqrt{\text{Raw Score}} \\ &= 10 \times \sqrt{75} \\ &= 10 \times 8.66 \\ &= 86.6 \\ &= 87\% \end{align}\]Sue does very poorly and makes a raw score of 25.
\[\begin{align} Score &= 10 \times \sqrt{\text{Raw Score}} \\ &= 10 \times \sqrt{25} \\ &= 10 \times 5 \\ &= 50 \\ &= 50\% \end{align}\]Jimmy's score went up 12 points, but Sue's score went up 25 points. Sue still has a poor grade, but it went up more than Jimmy's.
Square Root Curve Calculator
If you have a set of grades and don't want to do this by hand, enter them below. You only need to enter each grade once — duplicates are stripped out automatically.
Should you use it?
Using the square root curve, or any curve, is a question you have to answer for yourself.
One of my favorite administrator lines ever is "grades are totally at the teacher's purview." Of course, it was said to a student who'd come in to dispute their grade — not a fun situation. But it did make the point that even though a student earns their points, a teacher has the option of working the numbers as they see fit. If you see fit to curve a set of grades, or not, that's your decision.
Personally, I've used a square root curve a couple of times, but I prefer a linear grade distribution instead, scaling the top grade up to 100 and the low grade to 50 — assuming there are grades under 50 to begin with.