Muscle potential

Tool id: muscle-potential · Methods: casey-butt, ffmi-cap, berkhan

Men only in v1. Passing sex: "female" throws a DomainError. Female models are planned for a future release.

Estimate a realistic natural muscular ceiling; reach for it for a grounded long-term bodyweight target.

Input

Field	Type	Notes
sex	"male" | "female"	required — only "male" is supported in v1
height	{ value, unit }	cm or in — required
wrist	{ value, unit } | null	circumference — needed for casey-butt
ankle	{ value, unit } | null	circumference — needed for casey-butt
target_body_fat_pct	number	3–40 %, defaults to 10
methods	string[] | "all"	defaults to "all"

Methods

• casey-butt — Casey Butt’s model: drug-free maximum bodyweight derived from wrist and ankle circumferences. Requires wrist and ankle; skipped if absent.
• ffmi-cap — The FFMI ≈ 25 natural ceiling, back-calculated to bodyweight at the target body-fat %. Requires only height.
• berkhan — Martin Berkhan’s max-contest-weight rule of thumb. Requires only height.

Example

TypeScript

import { REGISTRY } from "@almostjacked/fitness-tools";
const mp = REGISTRY.get("muscle-potential")!;
mp.compute(mp.input.parse({
  sex: "male",
  height: { value: 180, unit: "cm" },
}));

curl

curl -s localhost:8080/v1/tools/muscle-potential \
  -X POST -H 'content-type: application/json' \
  -d '{"sex":"male","height":{"value":180,"unit":"cm"}}'

MCP

Call the muscle-potential tool with these arguments:

{
  "sex": "male",
  "height": { "value": 180, "unit": "cm" }
}

{
  results: [
    {
      method: "ffmi-cap",
      value: 90,
      unit: "kg",
      detail: { max_ffm_kg: 81, target_bf_pct: 10 },
    },
    {
      method: "berkhan",
      value: 84,
      unit: "kg",
      detail: { max_ffm_kg: 75.6, target_bf_pct: 10 },
    },
  ],
  consensus: { mean: 87, median: 87, min: 84, max: 90, n: 2 },
  skipped: [
    { method: "casey-butt", reason: "casey-butt: requires wrist and ankle" },
  ],
}

Call it another way

Full docs for the other protocols: HTTP API · MCP server.