Grade Curve Calculator
Curve grades by adding a fixed amount so the highest score reaches maximum, showing curved score, curve amount, and cap.
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Helping Notes
Curve points equal the difference between maximum possible and highest earned; add this same number to every student’s score.
Curved scores are capped at the maximum. This straight method preserves gaps between students while lifting the class uniformly.
Use points or percentages consistently. If using percentages, keep all three inputs as percent values.
Results
Curve Points Added
Curved Grade (Capped)
Uncapped Curved Grade
What Is Grade Curve Calculator?
The Grade Curve Calculator is a grading aid that transforms raw exam or assignment scores into adjusted, comparable results. It supports simple mean shifts, full z-score normalization to a target mean and standard deviation, percentile (quantile) mapping, and min–max rescaling to a chosen range. By showing every step—class mean, spread, chosen rule, and any caps—the tool helps instructors justify outcomes and helps students understand how adjustments were computed. Use it to stabilize grading when a test was unusually hard, align sections to a department policy, or translate ranks into letter bands with consistent thresholds. The calculator preserves transparency by pairing each output with the underlying formula so policies remain auditable across courses and terms.
About the Grade Curve Calculator
This calculator accepts raw scores (0–100 or any scale), computes class statistics (count, mean, standard deviation), and applies a selected curving method. Options include linear mean shift, z-score scaling to a target mean and standard deviation, percentile mapping (match each score’s rank to a target distribution), and min–max mapping to a chosen band (for example, 50–100). You can cap results at lower/upper bounds, round to policy increments, and map curved numbers to letters using editable cutoffs. For multi-component courses, it can curve each component separately, then combine with weights for a final mark. Because assumptions (targets, caps, rounding, letter thresholds) are explicit, results remain consistent and easy to explain.
How to Use this Grade Curve Calculator
1) Paste or enter raw scores. 2) Choose a method: mean shift, z-score scaling, percentile mapping, or min–max. 3) Set targets (mean and standard deviation, or range), plus optional caps and rounding step. 4) If using letters, set cutoffs (e.g., A ≥ 90, B ≥ 80, etc.). 5) For multi-component grading, curve components first, then apply weights to compute a final grade. 6) Review the summary: class stats, method details, curved scores, letter distribution, and any caps applied.
Examples Using the Grade Curve Calculator
Example A (z-score scaling): Raw mean μ=68, σ=12; target μt=75, σt=10. Student score x=83 → curved x′=75+10×(83−68)/12=87.5.
Example B (min–max to 0–100): Class min=42, max=96. Score x=78 → x′=0+(78−42)/(96−42)×100≈66.7.
Example C (percentile mapping): x is at the 84th percentile. With target Normal(75,10), z≈0.994 → x′≈75+10×0.994≈85.0.
Example D (reverse solve): Want x′=90 under Example A settings → required raw x=μ+σ×((90−μt)/σt)=68+12×1.5=86.
Core Formulas (rendered responsively)
Mean and population standard deviation of the raw scores.
Standardize a score relative to class mean and spread.
Map raw scores to a target mean \(\mu_t\) and standard deviation \(\sigma_t\).
Uniformly shifts all scores to reach a new mean while preserving spread.
Rescales to a target interval \([A,B]\).
Match ranks from the raw distribution to a target distribution.
Apply policy lower and upper bounds \(L,U\).
Combine curved components \(s'_j\) using weights \(w_j\).
Define letter bands in terms of standardized thresholds.
Snap results to policy increments \(r\) (e.g., 0.5 or 1.0).
FAQs
What does curving grades actually do?
It adjusts raw scores using a chosen rule so results align with a target mean/range or preserve percentile ranks.
Which method is “fairest” to use?
It depends on policy: z-score scaling preserves relative standing; percentile mapping preserves ranks; mean shift preserves spread.
Will curving change student rank?
Mean shift and z-score scaling keep order the same; percentile mapping also preserves rank by design.
How should I choose the target mean and standard deviation?
Base them on department norms, past cohorts, or rubric goals. Document the rationale before publishing results.
Should I cap curved scores at 100?
Many policies cap at 100 to avoid inflation; others allow extra credit. Set explicit bounds if needed.
Can I reverse-solve the raw score needed for a curved target?
Yes. Rearrange the chosen mapping (e.g., z-score formula) to solve the required raw value.
What if my class has strong outliers?
Consider percentile mapping or caps; outliers can distort mean/standard deviation in linear methods.
Does the calculator support multiple components?
Curve components separately (exams, projects), then combine with weights to compute a final grade.
Can I keep letter grades consistent across sections?
Yes—apply the same targets, caps, and letter thresholds to each section after computing their statistics.
Will curving always raise grades?
No. Some methods can lower high scores or compress spread. Review distributions before finalizing.
How transparent is the process for students?
Each result includes the formula and parameters used so students and reviewers can trace every adjustment.