Grade Curve Calculator › Flat Curve

Flat Curve Grading

A flat curve is the simplest adjustment there is: add the same number of points to every student. It takes seconds, it's effortless to explain, and for a small across-the-board correction it's often all you need.

What is a flat curve?

A flat curve (also called a flat boost or fixed adjustment) adds a constant number of points to each raw score. If you add 8 points, a 70 becomes 78 and a 55 becomes 63. Everyone moves up by the same amount, so the spacing and ranking between students stay exactly the same. It's the most intuitive curve for both teachers and students.

The flat curve formula

curved = original + X (capped at the maximum)

X is the number of points you add. The only wrinkle is the ceiling: a flat boost can push high scores past your maximum, so scores are capped at the top of the scale. That cap is also the method's main limitation — top students may get little or no benefit once they hit 100%.

The 10-point curve, explained

"Curve grades by 10 points" simply means a flat curve with X = 10:

• 58 → 68
• 74 → 84
• 93 → 100  (capped — only gained 7)

That last row shows the trade-off: students near the top hit the ceiling and gain less than 10. If that bothers you, a linear curve rescales the range instead of shifting it, avoiding the clip.

When should you use a flat curve?

• One or two questions were unfair and you want to refund those points to everyone.
• The whole class was slightly low and a small, transparent bump fixes it.
• You value simplicity over a more tailored distribution.

Skip it when top scores are already high (the cap wastes the boost) or when you specifically want to help strugglers more — a square root curve does that better.

Flat vs. other curves

The flat curve shifts; the linear curve stretches; the square root curve bends toward lower scores; and bell curve grading forces a distribution. Each has a moment — see them side by side in our pillar guide on how to curve grades.

Apply a flat curve in seconds

Pick the "add a fixed number of points" option, enter your boost, paste your scores, and review the capped results instantly. Export a CSV when you're happy.

Try the Flat Curve Calculator →

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