Grading Curve Calculator
Stretch or compress raw scores linearly onto a target range (e.g. class raw 20–70 → curved 40–95).
- 100% free
- No sign-up required
- Runs in your browser
- JSON API for agents
Curved scores
Raw range [40, 70] → [50, 95]
- 40 → 50
- 55 → 72.5
- 62 → 83
- 70 → 95
- 48 → 62
- 1.curved = 50 + (raw − 40) / (70 − 40) × (95 − 50)
- 2.Example: 40 → 50
Linear
Scale mapping
Live
Per-student preview
API
JSON curved list
How the linear curve works
Each block explains one part of how this works and how to read the result.
Set anchors
By default rawMin/rawMax are taken from the class data. Override them to pin specific anchors. Choose the target range you want after curving.
Source
Linear mapping: curved = targetMin + (raw − rawMin) / (rawMax − rawMin) × (targetMax − targetMin). One of several curve methods; not z-score or bell-curve forcing.
Frequently asked questions
Is this a bell curve?
No — it is a linear rescale. Bell-curve / forced-distribution grading is different and not implemented here.
Will the topper still be on top?
Yes, for a strictly increasing linear map (targetMax > targetMin and rawMax > rawMin).
Can scores exceed 100?
Only if your targetMax is above 100. Set targetMax to the paper maximum to avoid that.
What if everyone scored the same?
When rawMax = rawMin, every curved score equals targetMin and a warning is returned.
Related teacher & school planning tools
More free calculators and formats in the same lane.
For developers & AI agents
The Grading Curve Calculator is also available as a free, unauthenticated JSON API — no API key, no sign-up, CORS enabled for all origins. Send a GET request with the parameters below and receive the computed result as JSON, including the source of the format or formula used. Invalid input returns HTTP 400 with a JSON { "error": "..." } body.
GET https://knwdle.com/api/tools/grading-curve-calculator| Parameter | Required | Description |
|---|---|---|
scores | Yes | Comma-separated raw scores |
targetMin | Yes | Lower end of curved scale |
targetMax | Yes | Upper end of curved scale |
rawMin | No | Override raw minimum (default: class min) |
rawMax | No | Override raw maximum (default: class max) |
Request:
GET https://knwdle.com/api/tools/grading-curve-calculator?scores=40,55,62,70,48&targetMin=50&targetMax=95
Response:
{
"tool": "grading-curve-calculator",
"name": "Grading Curve Calculator",
"source": "Linear mapping: curved = targetMin + (raw − rawMin) / (rawMax − rawMin) × (targetMax − targetMin). One of several curve methods; not z-score or bell-curve forcing.",
"rawMin": 40,
"rawMax": 70,
"targetMin": 50,
"targetMax": 95,
"original": [
40,
55,
62,
70,
48
],
"curved": [
50,
72.5,
83,
95,
62
],
"flatInput": false,
"formula": "curved = 50 + (raw − 40) / (70 − 40) × (95 − 50)",
"steps": [
"Raw range = [40, 70]",
"Target range = [50, 95]",
"Example: raw 40 → 50"
]
}
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