Flat Curve Calculator
The simplest grading curve there is: find how many points the highest score is below 100 and add that many points to every grade. This calculator does the math for you.
A flat curve is the easiest curve there is: find the highest score on the test, figure out how many points it's below a perfect score, and add that same number of points to everybody's grade.
Enter your target score (usually 100) and every grade on the test, one per line, and this calculator will find the highest one, work out the difference, and apply it across the board.
The Math
Let's say the highest score on a test was a 92%. To bring that up to a perfect 100%, you'd add 8 points — and then add those same 8 points to every other score too.
\[\begin{align} Points\ Added &= Target - Highest\ Score \\ &= 100 - 92 \\ &= 8 \end{align}\]A student who scored a 75% would end up with a curved 83%, a student who scored a 61% would end up with a 69%, and so on — everyone gets the same flat bump.
When a flat curve makes sense
This is the curve most students picture when they ask "is there a curve?" It's quick, it's easy to explain, and it works well when a test was a little too hard across the board — a bad question or two, not enough time, whatever the reason.
What it doesn't do is help your lowest scores more than your highest ones. Everybody gets the same number of points, so a 95% and a 45% both go up by the same amount. If you want the lower scores to get more of a boost, take a look at the square root curve instead, or a linear grade distribution if you want full control over both ends.
Related Calculators
Also see the Square Root Curve, Linear Grade Distribution, and EZ Grader-style calculators.