{"uid":"cap_RRFF6UfVMOmDYEck4uC_g","slug":"boer-1984-lean-body-mass-fat-free-mass-calculator-9f67ca12","name":"Boer 1984 Lean Body Mass (Fat-Free Mass) Calculator","description":"Boer 1984 estimated lean body mass from sex, height_cm, and weight_kg (male 0.407W+0.267H-19.2; female 0.252W+0.473H-48.3). Reports lbm_kg (paper term) with ffm_kg as the same alias. Height 100-220 cm and weight 20-300 kg are magent clamps, not Boer bands. Not a dosing weight, James/Hume formula, or measured body composition. magent does not measure the patient.","url":"https://api.magentlab.com/api/calc/ffm","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET","HEAD","DELETE"],"type":"string"},"headers":{"type":"object","additionalProperties":{"type":"string"}},"queryParams":{"type":"object","required":["sex","weight_kg","height_cm"],"properties":{"sex":{"enum":["female","male"],"type":"string","description":"Sex used by Boer 1984 (separate male and female estimated lean-body-mass equations)."},"height_cm":{"type":"number","description":"Height in centimeters (100-220, magent clamp; Boer 1984 does not publish an input band)."},"weight_kg":{"type":"number","description":"Weight in kilograms (20-300, magent clamp; Boer 1984 does not publish an input band)."}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.005","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.005/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_yuj-JgvE8_fHihKCcRpi3","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.005","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Estimates lean body mass (LBM/FFM) in kilograms using the Boer 1984 sex-specific equations from height and weight inputs.","exampleAgentPrompt":"Using the Boer 1984 formula, estimate the lean body mass for a male patient who is 178 cm tall and weighs 85 kg.","exampleUseCases":[{"title":"ICU pharmacokinetics reference weight","prompt":"I need to look up the lean body mass for a female ICU patient who is 162 cm tall and weighs 110 kg — use the Boer 1984 equation."},{"title":"Obesity medicine body composition screen","prompt":"Can you calculate the fat-free mass for a male patient, 190 cm and 145 kg, using the Boer lean body mass formula?"},{"title":"Research cohort LBM normalization","prompt":"For my study I need the Boer 1984 estimated lean body mass for a female subject who is 155 cm tall and weighs 58 kg."}],"resultDescription":"Returns lbm_kg (lean body mass in kilograms), also aliased as ffm_kg (fat-free mass), computed via the Boer 1984 sex-specific linear regression equations. Male: 0.407×weight_kg + 0.267×height_cm − 19.2; Female: 0.252×weight_kg + 0.473×height_cm − 48.3. Inputs are clamped to height 100–220 cm and weight 20–300 kg by the API.","failureModes":["Missing required parameter (sex, weight_kg, or height_cm) returns a 4xx error","Height below 100 cm or above 220 cm triggers magent clamp behavior (clamped, not errored)","Weight below 20 kg or above 300 kg triggers magent clamp behavior","Invalid sex value (not 'male' or 'female') returns a validation error","Payment not provided or insufficient returns HTTP 402"],"whenToPreferThis":"Choose this endpoint when you specifically need the Boer 1984 estimated lean body mass equation and not the James, Hume, or Peters formulas. It is the right choice for reference weight computations in pharmacokinetics or anesthesia research workflows where Boer is the specified formula. Do not use this for actual body composition measurement, dosing weight (which has different conventions), or when a different LBM formula is required.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T06:59:30.327Z","isFirstParty":false}