# Mosteller BSA

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/bsa_mosteller`
HTML: https://magentlab.com/docs/bsa
Markdown: https://magentlab.com/docs/bsa.md

Not a medical device. Not a diagnosis, dose, or listing recommendation.

## What it computes

Compute Mosteller body surface area in m^2 from height and weight.

## When to use

When an agent needs BSA for oncology dosing arithmetic and must not let a model multiply.

## When not to use

- Not a dosing recommendation. The formula does not choose a regimen or round a vial.
- Height and weight must be provided in a consistent pair (cm/kg or in/lb).

## Formula

```
BSA_m2 = sqrt((height_cm * weight_kg) / 3600)
```

## Citation

Simplified calculation of body-surface area
Mosteller RD
N Engl J Med. 1987;317(17):1098
DOI: [10.1056/NEJM198710223171717](https://doi.org/10.1056/NEJM198710223171717)

## Worked example

### 170 cm, 70 kg

Given: `height_cm=170, weight_kg=70`

1. BSA = sqrt((170 * 70) / 3600) = sqrt(3.30555…) = 1.8181 m^2


## Parameters

- `height_cm` (number, optional): Height in centimeters. Provide height_cm or height_in.
- `weight_kg` (number, optional): Weight in kilograms. Provide weight_kg or weight_lb.
- `height_in` (number, optional): Height in inches. Converted as cm = in * 2.54.
- `weight_lb` (number, optional): Weight in pounds. Converted as kg = lb * 0.45359237.

## Bulk (POST)

POST the same path with a JSON items array. Price is n times the GET unit. Invalid items return HTTP 400 before settlement.

Method: `POST /api/calc/bsa_mosteller`
Max items: 25
Price: unit_amount * n (unit 5000 atomic)
Status: PREVIEW

- 1 to 25 items. Each item uses the same keys as the GET query parameters.
- The first invalid item fails the whole request (index in the 400 JSON). You are not charged.
- HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row.
- Catalog misses (empty matches, found=false) stay paid 200s inside that slot.
- x402 resource URL is this path plus n and body_sha256. Browsers that prefer text/html get the same paywall as GET; Pay retries POST with the same items.

Example request:

```json
{
  "items": [
    {
      "height_cm": "170",
      "weight_kg": "70"
    },
    {
      "height_cm": "170",
      "weight_kg": "70"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/bsa

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/bsa_mosteller",
  "items": [
    {
      "height_cm": 170.0,
      "weight_kg": 70.0,
      "disclaimer": "Not a medical device. Deterministic published-formula or coded-ontology output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Mosteller RD",
        "doi": "10.1056/NEJM198710223171717",
        "id": "mosteller-1987",
        "source": "N Engl J Med. 1987;317(17):1098",
        "title": "Simplified calculation of body-surface area"
      },
      "formula": "mosteller",
      "formula_expression": "BSA_m2 = sqrt((height_cm * weight_kg) / 3600)",
      "bsa_m2": 1.8181
    },
    {
      "height_cm": 170.0,
      "weight_kg": 70.0,
      "disclaimer": "Not a medical device. Deterministic published-formula or coded-ontology output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Mosteller RD",
        "doi": "10.1056/NEJM198710223171717",
        "id": "mosteller-1987",
        "source": "N Engl J Med. 1987;317(17):1098",
        "title": "Simplified calculation of body-surface area"
      },
      "formula": "mosteller",
      "formula_expression": "BSA_m2 = sqrt((height_cm * weight_kg) / 3600)",
      "bsa_m2": 1.8181
    }
  ]
}
```

## Response fields

- `formula` (string): mosteller
- `formula_expression` (string): Exact expression used
- `height_cm` (number): Normalized height in cm
- `weight_kg` (number): Normalized weight in kg
- `bsa_m2` (number): Body surface area in m^2, 4 decimal places
- `citation` (object): Peer-reviewed formula citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "height_cm": 170.0,
  "weight_kg": 70.0,
  "disclaimer": "Not a medical device. Deterministic published-formula or coded-ontology output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "citation": {
    "authors": "Mosteller RD",
    "doi": "10.1056/NEJM198710223171717",
    "id": "mosteller-1987",
    "source": "N Engl J Med. 1987;317(17):1098",
    "title": "Simplified calculation of body-surface area"
  },
  "formula": "mosteller",
  "formula_expression": "BSA_m2 = sqrt((height_cm * weight_kg) / 3600)",
  "bsa_m2": 1.8181
}
```

## Errors

- HTTP 400 `invalid_height`: height_cm (50-250) or height_in (20-98) is required Returned before settlement; you are not charged.
- HTTP 400 `invalid_weight`: weight_kg (1-500) or weight_lb (2-1100) is required Returned before settlement; you are not charged.
- HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
- HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
- HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged.
- HTTP 402 `payment_required`: Missing or invalid PAYMENT-SIGNATURE; decode the PAYMENT-REQUIRED header
- HTTP 409 `payment_in_progress`: The same authorization nonce is already being settled; retry shortly
- HTTP 429 `rate_limited`: Too many requests from this client
- HTTP 503 `settlement_uncertain`: Settlement is unconfirmed; retry with the same PAYMENT-SIGNATURE
- HTTP 503 `facilitator_unavailable`: Payment facilitator unavailable
- HTTP 503 `facilitator_misconfigured`: Payment facilitator is not configured
- HTTP 503 `facilitator_unauthorized`: Payment facilitator rejected credentials
- HTTP 503 `ledger_unavailable`: Payment ledger unavailable
- HTTP 503 `payment_unavailable`: Payment processing unavailable

## Related tools

- [BMI](https://magentlab.com/docs/bmi) — Compute Keys/Quetelet body-mass index from height and weight, plus a WHO adult band.
- [Devine IBW](https://magentlab.com/docs/ibw) — Compute Devine ideal body weight and 0.4 adjusted body weight from height, sex, and actual weight.

## Also searched as

- Mosteller formula
- body surface area
- oncology BSA
- m2 BSA

## Payment

Required query parameters must be present and valid. Invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s.

## Guarantees

- Invalid query parameters return HTTP 400 before settlement. You are not charged.
- Settlement finishes before the tool executes. Uncertain settlement fails closed (HTTP 503).
- Execution is timeout-bounded and concurrency-capped.
- Calculator inputs are not persisted. Request logs store path without query.