Fluids · LIVE

Adult Wallace rule of nines

Rule of nines

Sum Wallace 1951 adult region percents from caller-assigned none/half/full fractions to a percent TBSA.

LIVE $0.005 USDC GET /api/calc/rule_of_nines

Markdown: /docs/rule-of-nines.md · Canonical: https://magentlab.com/docs/rule-of-nines

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

What it computes

Sum Wallace 1951 adult region percents from caller-assigned none/half/full fractions to a percent TBSA.

When to use

When an agent needs adult Wallace rule-of-nines TBSA arithmetic and must not apply Lund-Browder pediatric percents or invent a Parkland fluid volume.

When not to use

• Not a medical device. Deterministic Wallace 1951 adult percent arithmetic only.
• Adult chart only. Not Lund-Browder (pediatric) percentages.
• magent does not examine the burn. Region fractions are caller-assigned (0 none, 0.5 half, 1 full).
• Not a Parkland fluid order. Parkland takes tbsa_percent separately.

Formula

tbsa_percent = head*9 + arm_left*9 + arm_right*9 + anterior_trunk*18 + posterior_trunk*18 + leg_left*18 + leg_right*18 + perineum*1 (Wallace 1951 adult percents; each factor is 0, 0.5, or 1)

Citation

Title

The exposure treatment of burns

Authors

Wallace AB

Source

Lancet. 1951;1(6653):501-504

DOI

10.1016/s0140-6736(51)91975-7

Worked example

Also searched as

• Wallace rule of nines
• adult TBSA
• burn surface area percent
• Wallace 1951 burns
• adult burn chart
• rule of 9s
• anterior trunk 18 percent
• TBSA from regions

Try

Opens the live endpoint. Unpaid browser requests show the paywall; agents should send Accept: application/json.

/api/calc/rule_of_nines?head=0&arm_left=0&arm_right=0&anterior_trunk=1&posterior_trunk=0&leg_left=0&leg_right=0&perineum=0

Full URL: https://api.magentlab.com/api/calc/rule_of_nines?head=0&arm_left=0&arm_right=0&anterior_trunk=1&posterior_trunk=0&leg_left=0&leg_right=0&perineum=0

Call

Expect HTTP 402 until you retry with PAYMENT-SIGNATURE. Incomplete query params return HTTP 400 before any quote or charge.

curl -i -H "Accept: application/json" "https://api.magentlab.com/api/calc/rule_of_nines?head=0&arm_left=0&arm_right=0&anterior_trunk=1&posterior_trunk=0&leg_left=0&leg_right=0&perineum=0"

Parameters

Bulk (POST)

POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement.

POST /api/calc/rule_of_nines Max 25 unit_amount + extra_item_amount * (n - 1) extra $0.002 PREVIEW

• 1 to 25 items. Each item uses the same keys as the GET query parameters.
• POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows.
• 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 (fixture)

{
  "items": [
    {
      "anterior_trunk": "1",
      "arm_left": "0",
      "arm_right": "0",
      "head": "0",
      "leg_left": "0",
      "leg_right": "0",
      "perineum": "0",
      "posterior_trunk": "0"
    },
    {
      "anterior_trunk": "1",
      "arm_left": "0",
      "arm_right": "0",
      "head": "0",
      "leg_left": "0",
      "leg_right": "0",
      "perineum": "0",
      "posterior_trunk": "0"
    }
  ]
}

Open bulk paywall →

Opens a two-item fixture on the API host. Unpaid browsers get the same MetaMask paywall as GET; Pay retries POST with those items.

Example 200 (fixture)

{
  "count": 2,
  "path": "/api/calc/rule_of_nines",
  "items": [
    {
      "head": 0.0,
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Wallace AB",
        "doi": "10.1016/s0140-6736(51)91975-7",
        "id": "wallace-1951",
        "pmid": "14805109",
        "source": "Lancet. 1951;1(6653):501-504",
        "title": "The exposure treatment of burns"
      },
      "formula": "rule_of_nines",
      "formula_expression": "tbsa_percent = head*9 + arm_left*9 + arm_right*9 + anterior_trunk*18 + posterior_trunk*18 + leg_left*18 + leg_right*18 + perineum*1 (Wallace 1951 adult percents; each factor is 0, 0.5, or 1)",
      "tbsa_percent": 18.0,
      "anterior_trunk": 1.0,
      "arm_left": 0.0,
      "arm_right": 0.0,
      "leg_left": 0.0,
      "leg_right": 0.0,
      "perineum": 0.0,
      "posterior_trunk": 0.0
    },
    {
      "head": 0.0,
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Wallace AB",
        "doi": "10.1016/s0140-6736(51)91975-7",
        "id": "wallace-1951",
        "pmid": "14805109",
        "source": "Lancet. 1951;1(6653):501-504",
        "title": "The exposure treatment of burns"
      },
      "formula": "rule_of_nines",
      "formula_expression": "tbsa_percent = head*9 + arm_left*9 + arm_right*9 + anterior_trunk*18 + posterior_trunk*18 + leg_left*18 + leg_right*18 + perineum*1 (Wallace 1951 adult percents; each factor is 0, 0.5, or 1)",
      "tbsa_percent": 18.0,
      "anterior_trunk": 1.0,
      "arm_left": 0.0,
      "arm_right": 0.0,
      "leg_left": 0.0,
      "leg_right": 0.0,
      "perineum": 0.0,
      "posterior_trunk": 0.0
    }
  ]
}

Response

Example JSON

Machine form of the same example. Frozen fixture. Not a live lookup.

{
  "head": 0.0,
  "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "citation": {
    "authors": "Wallace AB",
    "doi": "10.1016/s0140-6736(51)91975-7",
    "id": "wallace-1951",
    "pmid": "14805109",
    "source": "Lancet. 1951;1(6653):501-504",
    "title": "The exposure treatment of burns"
  },
  "formula": "rule_of_nines",
  "formula_expression": "tbsa_percent = head*9 + arm_left*9 + arm_right*9 + anterior_trunk*18 + posterior_trunk*18 + leg_left*18 + leg_right*18 + perineum*1 (Wallace 1951 adult percents; each factor is 0, 0.5, or 1)",
  "tbsa_percent": 18.0,
  "anterior_trunk": 1.0,
  "arm_left": 0.0,
  "arm_right": 0.0,
  "leg_left": 0.0,
  "leg_right": 0.0,
  "perineum": 0.0,
  "posterior_trunk": 0.0
}

Client errors (HTTP 400)

Invalid params return 400 without charge. Shared HTTP 402 and 503 meanings: Payments.

Related tools

• Parkland formula — Compute adult Parkland 24-hour crystalloid volume from weight and percent TBSA, with half allotted to the first 8 hours from the time of burn.

Payment

Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, 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. Unpaid valid requests return HTTP 402 with a base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote: retry the same PAYMENT-SIGNATURE. Full handshake and shared payment errors: Payments. Stdio MCP: /docs/mcp.

Guarantees

• HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. HTTP 402 never includes the tool JSON.
• exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. Uncertain or failed settlement fails closed (HTTP 503). Retry the same PAYMENT-SIGNATURE.
• HTTP 402 is unpaid only. Do not sign a second authorization because of a 503.
• Execution is timeout-bounded and concurrency-capped.
• Calculator inputs are stored encrypted for allowlisted operators (Magent Console). They are not in public logs, SSH lookups, catalog, or rollups. Request logs store path without query.