📈 Grade Curve Calculator

Paste a list of raw test scores and apply a curve method to see the curved scores and before/after averages.

Raw Scores (one per line, 0-100)

Curve Method

Flat Bonus Points

The three curves

Each raw score is transformed independently and then capped, so nothing can finish above 100:

Highest to 100   curved = min(100, raw + (100 - highest raw))
Square root      curved = min(100, 10 × √raw)
Flat bonus       curved = min(100, raw + bonus points)

On the seven sample scores the class average is 67.6. Shifting the top score of 90 up to 100 adds 10 to everyone and moves the average to 77.6. The square root curve moves it to 81.8, but unevenly: the 45 becomes 67.1 while the 90 becomes only 94.9.

Choosing between them

Highest to 100 assumes the top scorer found the ceiling and the paper was simply too long or too hard. It keeps every gap between students exactly as it was.
Square root compresses the class upward, giving the largest lift to the weakest scores and almost none near the top. Use it when a question was badly worded rather than when the whole paper was hard.
Flat bonus is the transparent one - state the number of points and everyone can check it. The cap means students already near 100 gain less than the rest.

All three preserve rank order: nobody overtakes anybody, and no score is ever reduced. Scores must be numbers from 0 to 100, one per line; anything outside that stops the calculation rather than being ignored.

Frequently asked questions

What does a square root curve do to a 45?

It becomes 67.1, since the square root of 45 is 6.708 and the tool multiplies by 10. The same curve lifts an 81 to 90 and leaves a 100 at 100, which is why it is described as helping the bottom of the class most.

Is this the same as grading on a bell curve?

No. A true bell curve fixes the share of the class receiving each letter, so one student's grade depends on everyone else's. These three methods adjust scores and leave the letter boundaries alone.

How many points is a fair flat bonus?

Match it to the damage: if one 5 point question was unanswerable, add 5. A larger bonus is really a statement that the whole paper was mis-set, which the highest-to-100 method expresses more honestly.