Curve an exam score using four methods: flat boost, square-root (Texas) curve, scale to class top, or bell-curve remap.
Raw
72
Curved
80
Calculator
Curved score
80
+8 pts above raw
Raw vs. curved
Raw
72
Curved
80
How grade curves work
A flat (linear) curve simply adds a fixed number of points to every score and caps at 100. The square-root, or Texas, curve takes the square root of each score and multiplies by 10, which benefits lower scores more than higher ones. Scale-to-top adjusts every score proportionally so that the class-best raw score becomes exactly 100.
The bell curve remap standardises each score into a z-score then rescales it to a new distribution with your chosen mean and standard deviation. It preserves relative rank perfectly, while shifting the class average to any target you like.
Which curve method is fairest?
It depends on the goal. The flat curve is the simplest — every student gains the same absolute points. The square-root curve benefits struggling students the most. Scale-to-top only adjusts when the class maximum is below 100, keeping rank distances intact. The bell curve is the most powerful but requires knowing (or estimating) the class mean and standard deviation.
What is the Texas (square-root) curve?
The Texas curve multiplies the square root of a raw score by 10. A student who scored 64 earns 80 after curving (sqrt(64) × 10), while a student who scored 81 earns 90 (sqrt(81) × 10). Scores closer to 0 receive the biggest boost.
Can the curved score exceed 100?
No — all methods clamp the result to 100. If your flat-curve addition would push a score above 100, the calculator reports 100.
Results are estimates. Verify with a professional for important decisions.
About this calculator
A grade curve adjusts raw exam scores upward so that the class distribution better reflects intended performance standards. This calculator supports four common curving methods: a flat point addition, the square-root "Texas" curve, a linear scale-to-top, and a statistical bell-curve remap. Enter your raw score and the relevant class parameters to see your curved result instantly.
How to read your results
The headline figure is your curved score on a 0–100 scale. Below it, the Score Comparison bar chart draws two horizontal bars side by side — the grey bar is your raw score and the coloured bar is your curved score — both scaled so the full bar width equals 100. The delta line beneath the headline tells you exactly how many points were added (or subtracted) by the curve.
Worked example
Raw score: 72. Method: flat addition of 8 points.
72 + 8 = 80. The curved score is 80, an increase of 8 points.
Frequently asked questions
What is the square-root (Texas) curve?
Popularised in Texas high schools, this method sets your curved score to √(raw score) × 10. A raw 72 becomes √72 × 10 ≈ 84.9. Lower scores receive a larger boost than higher ones, compressing the distribution toward the top.
How does the linear scale-to-top method work?
The highest raw score in the class is scaled to exactly 100, and every other score is scaled proportionally. If the class top is 90 and your raw score is 72, your curved score is 72 × 100 / 90 = 80.
What does the bell-curve remap do?
The bell-curve method uses z-scores to shift and stretch the class distribution. Your raw score is standardised using the class mean and standard deviation, then re-expressed in a new distribution with a different target mean and target standard deviation. For example, a raw 72 with class mean 70, SD 10, remapped to target mean 75, target SD 10 gives a curved score of 77.
Will my curved score ever exceed 100?
No. All four methods clamp the result to the range 0–100, so no curved score can exceed a perfect 100 or drop below 0.
Which curving method should I use?
Flat addition is the simplest and most transparent. Square-root curves help struggling students more than high achievers. Scale-to-top is fair when the exam was genuinely too hard. Bell-curve remap is best when you want to shift the whole class to a specific grade distribution.
How it's calculated
Flat curve: curvedScore = rawScore + points, clamped to [0, 100]. Square-root curve: curvedScore = √rawScore × 10, clamped to [0, 100]. Linear scale-to-top: curvedScore = rawScore × 100 / topRawScore, clamped to [0, 100]. Bell-curve remap: the raw score is converted to a z-score relative to the class distribution — z = (rawScore − mean) / sd — then placed on the target distribution: curvedScore = targetMean + z × targetSd, clamped to [0, 100]. All four formulas are standard statistical and educational techniques; see the calculator sources for worked examples from Omni Calculator and Grade Calculator.
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