Curve grades or scores in Microsoft Excel by using a simple addition formula to add a set number of points to each score. This method assumes a simple curve where each score is increased by the same number of points.
Create a new spreadsheet with three columns, and assign the following names to the columns from left to right: student name, raw score and curved score. If needed wish, add separate columns for first and last names, ID numbers and so on.
Populate the cells in the name column with each student's name. In the corresponding raw score column, list the actual, non-curved score. The third column will contain a formula that adds the desired number of points to each score. For example, if the raw score for a student is located in cell B2 and five points need to be added to each score, the formula would read "=B2+5."
Another method involves creating a spreadsheet with the following columns: possible scores, raw scores, curved scores and student names. To calculate the curve, multiply 100 to factor of the difference between one and your curve amount reported as a percentage in decimal form, which is then multiplied by the raw score to the power of the curve amount. Therefore, cell B2 contains the raw student score, the curve amount is .5, the formula would read "=100^(1-.5)*B2^.5." Note that the higher the curve amount, the less impact the formula has. If the curve amount is 1, the scores remain virtually unchanged while a curve amount of 0 will make virtually all scores either 0 or 100.