Grading curve calculator
A grading curve adjusts a set of scores so the class’s results fit a target, usually when a test proved harder than intended. This calculator applies one of two curves to every score: an additive curve, which adds the same number of points to everyone, or a scaled curve, which multiplies every score by the same factor. In both, the highest score becomes the target you set, 100 by default.
Paste the raw scores, one per line or separated by commas. The table shows each score before and after the curve, rounded to two decimal places. The arithmetic runs in your browser.
One per line, or separated by commas.
Added 15 points to every score (the highest was 85). Scores stop at 100.
| Raw | Curved |
|---|---|
| 62 | 77 |
| 70 | 85 |
| 78 | 93 |
| 85 | 100 |
How to use it
- Paste the raw scores, one per line or separated by commas. Use the scores on the same scale the test was marked on.
- Choose the method. Additive adds points; scaled multiplies.
- Leave the target at 100, or set the score you want the highest raw score to reach.
- Read the curved column. Record which method you used and the raw scores, so the adjustment can be explained to students.
The two methods
An additive curve adds the same number of points to every score. The points added equal the target minus the highest raw score. With the highest score at 85 and a target of 100, every score rises by 15, and anything that would pass 100 stops at 100.
A scaled curve multiplies every score by the target divided by the highest raw score. With the highest score at 85, every score is multiplied by 100 divided by 85, about 1.1765. A score of 0 stays 0, and the gaps between scores grow in proportion.
A worked example, checked by hand
Raw scores of 62, 70, 78 and 85. The highest is 85, so an additive curve adds 15: the scores become 77, 85, 93 and 100. A scaled curve multiplies by 100 divided by 85: 62 becomes 72.94, 70 becomes 82.35, 78 becomes 91.76 and 85 becomes 100.
Both curves put the top score at 100. The additive curve keeps every gap between scores the same as in the raw marks (8, 8 and 7 points). The scaled curve widens them, from 8 points to about 9.4 between the 70 and 78.
Limits of this tool
Both curves follow the target: if the target is below the highest raw score, the scores fall rather than rise. The tool allows that only so you can see the effect. A curve can also be distorted by a single unusually high or low score, which is why many teachers check the question analysis before curving.
Votense does not apply a curve to quiz or exam results. Exam mode uses a pass mark and grade bands that you set, and manual marks on the Grade screen override automatic ones. Curve the numbers here, then set the bands or marks to match.
Use it with a real vote, quiz or test
Votense is free to start: no card, and creating a poll, quiz or exam does not need a plan.
Grading curve calculator questions
- Which curve should I use?
- It depends on what you want the curve to do. An additive curve lifts every student by the same number of points, which is easy to explain. A scaled curve lifts students in proportion to their score, which keeps a zero at zero. Pick one before you look at the results, and use the same method for the whole class.
- Can a curve lower a score?
- Only if the target is below the highest raw score, because both methods are anchored to that target. With the default target of 100 and a highest score under 100, no score falls.
- Does Votense curve grades automatically?
- No. Votense exam mode grades against a pass mark and grade bands that you set, and you can override any automatic mark on the Grade screen. Use this calculator to work out curved numbers, then enter them as the bands or marks you want.
- Should I curve when one question was faulty?
- Often it is fairer to remove that question, or give every student the marks for it, than to curve the whole test. Removing a question changes each student’s total, not the scale of the whole class.