{"uid":"cap_SnQvSpSlsdHaBNnTEnypX","slug":"saylor-innovations-body-fat-calculator-us-navy-method-5796bc52","name":"Saylor Innovations Body Fat Calculator (US Navy Method)","description":"Body fat percentage from tape measurements using the US Navy method with ACE category, healthy range and fat and lean mass when weight is supplied","url":"https://saylorinnovations.com/api/health/body-fat?utm_source=zero.xyz","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"],"type":"string"},"queryParams":{"type":"object","required":["sex","height_cm","neck_cm","waist_cm"],"properties":{"sex":{"type":"string","description":"male or female"},"neck_cm":{"type":"string","description":"Neck circumference in cm"},"waist_cm":{"type":"string","description":"Waist circumference in cm"},"height_cm":{"type":"string","description":"Height in cm"},"weight_kg":{"type":"string","description":"optional, to compute fat and lean mass"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string","const":"json"},"example":{"type":"object","required":["sex","body_fat_percent","category"],"properties":{"sex":{"type":"string","description":"Sex used in the formula"},"note":{"type":"string","description":"Caveat or context for reading the result"},"inputs":{"type":["object","null"],"description":"Measurements used: height, neck, waist and hip in cm"},"method":{"type":"string","description":"Method used"},"source":{"type":"string","description":"Data source the values come from"},"category":{"type":"string","description":"Category"},"fat_mass_kg":{"type":["number","null"],"description":"Fat mass, in kilograms"},"lean_mass_kg":{"type":["number","null"],"description":"Lean mass, in kilograms"},"body_fat_percent":{"type":"number","description":"Body fat, as a percentage"},"healthy_range_percent":{"type":"string","description":"Healthy range, as a percentage"}}}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.01","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":"$0.01/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_u1PLFTgQUD5JJSm85i6Ym","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.01","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Calculates body fat percentage from tape measurements using the US Navy formula, returning ACE category, healthy range, and optionally fat and lean mass in kg","exampleAgentPrompt":"Can you calculate my body fat percentage using the US Navy tape-measure method? I'm male, 178 cm tall, neck is 38 cm, waist is 85 cm, and I weigh 80 kg.","exampleUseCases":[{"title":"Personal body composition check","prompt":"I want to know my body fat percentage and what category I fall into — I'm female, 165 cm tall, my neck is 33 cm, waist is 72 cm, and hips are 95 cm. I weigh 62 kg so also tell me my fat and lean mass."},{"title":"Fitness app integration for clients","prompt":"Calculate body fat for a male client who is 183 cm tall, has a 40 cm neck and 90 cm waist — he weighs 88 kg. I need the category, healthy range, and both fat mass and lean mass."},{"title":"Military or sports readiness assessment","prompt":"Run a US Navy body fat check on me: I'm male, 175 cm, neck circumference 37 cm, waist 82 cm. Just give me the percentage and whether I'm in the healthy range."}],"resultDescription":"Returns a JSON object with the computed body fat percentage, the ACE category (e.g. Fitness, Acceptable, Obese), the healthy range as a percentage string, the method and source used, the inputs echoed back, and — if weight was provided — fat mass and lean mass in kilograms, plus an optional note for context.","failureModes":["Missing required query parameters (sex, height_cm, neck_cm, waist_cm) result in an error response","Invalid or non-numeric values for measurements may cause calculation failure","Unrealistic measurement values (e.g. neck larger than waist) may produce nonsensical but technically computed results","Hip measurement may be required for female calculations — omitting it for female inputs could cause an error","Network or upstream service downtime returns a non-200 response"],"whenToPreferThis":"Choose this endpoint when you need a quick, formula-based body fat estimate from simple tape measurements without requiring expensive lab tests or body scan equipment. It is ideal for fitness, wellness, or health-tracking agents that need to classify body composition using the widely-accepted US Navy method. Prefer it over BMI-based endpoints when you want a more accurate fat-vs-lean breakdown, and over DEXA or bioimpedance APIs when only circumference measurements are available.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-18T12:56:24.807Z","isFirstParty":false,"canonicalSlug":"saylor-innovations-body-fat-calculator-us-navy-method-5796bc52"}