Calc Rfm
by magent in Other
Relative fat mass (RFM) from height, waist, and sex (Woolcott 2018). Height and waist in meters in the paper; magent accepts height_cm or height_in and waist_cm. Deterministic published arithmetic with citation. Not a medical device, not a body-fat diagnosis, and not later obesity cutoffs. magent does not measure the patient.
https://api.magentlab.com/api/calc/rfm- Price
- $0.007
- per call in USDC
- Uptime
- 100%
- last 30 days
- Response time
- 163 ms
- 413 ms slowest 5%
- Last check
- Passed
- 1 h ago, next any minute now
Reliability
Status and outage history · Atom feed · Watch with other listings
How to call it
POST https://api.magentlab.com/api/calc/rfm
Each call costs $0.007 in USDC on Base, paid with the request over x402.
Run a free test callOne unpaid request, the way an agent sends it. You see the payment challenge it gets back. Nothing is charged.
Example request
From the listing.
POST https://api.magentlab.com/api/calc/rfm
content-type: application/json
{
"items": [
{
"height_cm": 180,
"height_in": 70,
"sex": "male",
"waist_cm": 90
},
{
"height_cm": 180,
"height_in": 70,
"sex": "male",
"waist_cm": 90
}
]
}Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
items | array of object | Yes |
Example response
The provider's example. We can't check it without paying.
Example response, 40 lines
{
"count": 2,
"items": [
{
"citation": {
"authors": "Woolcott OO, Bergman RN",
"doi": "10.1038/s41598-018-29362-1",
"id": "woolcott-2018",
"pmid": "30030479",
"source": "Sci Rep. 2018;8:10980",
"title": "Relative fat mass (RFM) as a new estimator of whole-body fat percentage ─ A cross-sectional study in American adult individuals"
},
"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.",
"formula": "rfm",
"formula_expression": "RFM = 64 - (20 * (height_m / waist_m)) + (12 * sex); sex = 0 male, 1 female",
"height_cm": 180,
"rfm": 24,
"sex": "male",
"waist_cm": 90
},
{
"citation": {
"authors": "Woolcott OO, Bergman RN",
"doi": "10.1038/s41598-018-29362-1",
"id": "woolcott-2018",
"pmid": "30030479",
"source": "Sci Rep. 2018;8:10980",
"title": "Relative fat mass (RFM) as a new estimator of whole-body fat percentage ─ A cross-sectional study in American adult individuals"
},
"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.",
"formula": "rfm",
"formula_expression": "RFM = 64 - (20 * (height_m / waist_m)) + (12 * sex); sex = 0 male, 1 female",
"height_cm": 180,
"rfm": 24,
"sex": "male",
"waist_cm": 90
}
],
"path": "/api/calc/rfm"
}Call it from code
The curl command shows the payment challenge. The JavaScript and Python versions pay and call, and never pay more than $0.007.
curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://api.magentlab.com/api/calc/rfm' \
-H 'content-type: application/json' \
--data-raw '{"items":[{"height_cm":180,"height_in":70,"sex":"male","waist_cm":90},{"height_cm":180,"height_in":70,"sex":"male","waist_cm":90}]}'
# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - -X POST 'https://api.magentlab.com/api/calc/rfm' \
-H 'content-type: application/json' \
--data-raw '{"items":[{"height_cm":180,"height_in":70,"sex":"male","waist_cm":90},{"height_cm":180,"height_in":70,"sex":"male","waist_cm":90}]}' \
| grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decodeJavaScript: pay and call
// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";
// Pays at most $0.007 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.007" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);
// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.007 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fapi.magentlab.com%2Fapi%2Fcalc%2Frfm&method=POST
const res = await pay("https://api.magentlab.com/api/calc/rfm", {
method: "POST",
headers: { "content-type": "application/json" },
body: JSON.stringify({
"items": [
{
"height_cm": 180,
"height_in": 70,
"sex": "male",
"waist_cm": 90
},
{
"height_cm": 180,
"height_in": 70,
"sex": "male",
"waist_cm": 90
}
]
}),
});
console.log(res.status, await res.text());Python: pay and call
# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client
# Pays at most $0.007 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.007"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))
with x402_requests(client) as session:
res = session.post(
"https://api.magentlab.com/api/calc/rfm",
json={
"items": [
{
"height_cm": 180,
"height_in": 70,
"sex": "male",
"waist_cm": 90,
},
{
"height_cm": 180,
"height_in": 70,
"sex": "male",
"waist_cm": 90,
},
],
},
)
print(res.status_code, res.text)Security scan
1 finding
- Charges more than its listed price in payment
Listed at $0.005, charges $0.007
Recent checks
| When | Result | HTTP | Time | Price |
|---|---|---|---|---|
| 1 h ago | Passed | 402 | 180 ms | $0.007 |
| 6 h ago | Passed | 402 | 145 ms | $0.007 |
| 11 h ago | Passed | 402 | 230 ms | $0.007 |
| 15 h ago | Passed | 402 | 240 ms | $0.007 |
| 20 h ago | Passed | 402 | 217 ms | $0.007 |
Show 10 older checks
| 24 h ago | Passed | 402 | 134 ms | $0.007 |
| 28 h ago | Passed | 402 | 315 ms | $0.007 |
| 32 h ago | Passed | 402 | 201 ms | $0.007 |
| 36 h ago | Passed | 402 | 275 ms | $0.007 |
| 41 h ago | Passed | 402 | 291 ms | $0.007 |
| 45 h ago | Passed | 402 | 131 ms | $0.007 |
| 2 days ago | Passed | 402 | 250 ms | $0.007 |
| 2 days ago | Passed | 402 | 137 ms | $0.007 |
| 2 days ago | Passed | 402 | 140 ms | $0.007 |
| 3 days ago | Passed | 402 | 142 ms | $0.007 |
History
| 11 Oct 2026 | Price changed from $0.005 to $0.007 |