Test Curve Calculator
Calculations for Curving Test Scores Made Easy
Updated

This page is intended to help teachers curve tests. Normally, I am not a fan of "grading on the curve" but we all know there are times when it is called for.

If you are not curving a test, put 0 into the bottom box (the one for the number of questions wrong to get full credit) and this becomes just a standard grade chart.

You can also print this page, or just "copy and paste" the data from the table you want into a word processor. If you do this, use a fixed-pitch font like "Courier" to make everything line up.

Push the "Calculate Tables" button to fill the tables with values. Default values are entered for purposes of illustration. Change them to your values and push the "Calculate Tables" button again. To go back to the default values, push the "Restore Defaults" button.

These assumptions, along with work-arounds are discussed below in the Read More section below.

Weight of Test (advertised number of points value)
Number of Questions
Number of Questions Wrong to Still Receive Full Credit (assumes all are equally weighted).

 Zero-Base Table # Wrong Score Addition Table # Wrong Score

1. All questions on a test have equal value.
If they don't, then you will have to adjust the "Number Wrong" and "Total Questions" appropriately. For example, if a 40-question test has 10 questions with twice the weight of the other 30 questions, count it as a 50 question test (30 * 1 + 10 * 2 = 50) and mark off two wrong for each double-weight question that is wrong.

2. All scores are rounded to the nearest whole point.
If you want to go to tenths, just put 10 times the intended point value of the test in the "Weight of Test" box and divide by ten in your head. I may improve this, if anyone thinks this is needed.

Both tables allow scores above the supposed maximum if any students scored above the target number of right answers. That is inherent in the "curving" process. You can leave these as bonus points for those who did well, or round them down to the maximum for the test. Your choice.
1. "Zero-Base" Table.
In the Zero-Base table a student who gets no right answers gets no points. The number of points for each correct value is increased to give the full point value for the test when the required number of correct answers is reached. This means that the maximum possible score is higher than in the Addition table, because each right answer is worth more points than would be the case on an "uncurved" test.
In the Addition table enough points are added to the test score to make the target number of wrong answers equal the full value of the test. This has the (possibly) unintended consequence of giving out points even when there are no right answers. Also, it slightly penalizes those on the top end, because right answers are in effect only worth what they would have been if the test had not been curved, but a fixed number of points has been added.