{"uid":"cap_qI6uw7yJR8xMxf3pDLEzg","slug":"us-navy-body-fat-percentage-calculator-f900b166","name":"US Navy Body Fat Percentage Calculator","description":"Body fat percentage estimate from tape measurements (US Navy method) with fat mass, lean mass and a general category.","url":"https://fitness-calc.x402tookit.com/body-fat-navy?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","neck","waist"],"properties":{"hip":{"type":"number","description":"Hip at the widest point (required for women)"},"sex":{"type":"string","description":"male or female"},"neck":{"type":"number","description":"Neck circumference below the larynx"},"units":{"type":"string","description":"metric (cm, kg; default) or imperial (inches, lb)"},"waist":{"type":"number","description":"Waist at the navel (men) or narrowest point (women)"},"height":{"type":"number","description":"Height"},"weight":{"type":"number","description":"Body weight to also give fat and lean mass"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"sex":{"type":["null","string"]},"asOf":{"type":["null","string"]},"source":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"summary":{"type":["null","string"]},"verdict":{"type":["null","string"]},"category":{"type":["null","string"]},"degraded":{"type":["boolean","null"]},"fatMassKg":{},"bodyFatPct":{"type":["null","number"]},"disclaimer":{"type":["null","string"]},"leanMassKg":{},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"inputsInches":{"type":["null","object"],"properties":{"hip":{},"neck":{"type":["null","number"]},"waist":{"type":["null","number"]},"height":{"type":["null","number"]}}}}}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.02","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":"$0.02/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_FCBJK4f7fGUDiCWu8o5Tb","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Estimates body fat percentage using the US Navy tape-measure method, returning fat mass, lean mass, and body composition category from circumference measurements.","exampleAgentPrompt":"I'm a 5'11\" male weighing 185 lbs — can you estimate my body fat percentage using the Navy method? My neck is 16 inches, my waist is 34 inches, and use imperial units.","exampleUseCases":[{"title":"Personal body composition check","prompt":"I'm a woman, 165 cm tall, 68 kg. My neck is 33 cm, waist is 74 cm, and hip is 97 cm. Can you calculate my body fat percentage using the Navy tape method and tell me what category I fall into?"},{"title":"Fitness tracking for male athlete","prompt":"Help me track my body composition — I'm male, 6 feet tall, 190 pounds, neck 15.5 inches, waist 32 inches. Use imperial units and also tell me how much of my weight is fat vs lean mass."},{"title":"Military or occupational body fat assessment","prompt":"I need to check if my body fat meets military standards. I'm a male, 70 inches tall, neck 15 inches, waist 36 inches, weight 210 lbs — run the US Navy body fat formula and give me the result in imperial units."}],"resultDescription":"Returns the estimated body fat percentage (bodyFatPct), fat mass in kg (fatMassKg), lean mass in kg (leanMassKg), a body composition category (e.g. 'fitness', 'obese'), the sex used, input measurements converted to inches, a summary verdict, and a medical disclaimer. Includes a degraded flag and reasons array if any inputs were outside expected ranges.","failureModes":["Missing required parameters (sex, height, neck, waist) returns an error","Hip measurement missing for female input causes failure","Out-of-range measurements (e.g. negative or implausibly large values) may return degraded result with reasons","Invalid unit string (not 'metric' or 'imperial') may default to metric or return an error","Weight not provided means fat mass and lean mass cannot be computed (only percentage returned)"],"whenToPreferThis":"Use this endpoint when you need a non-invasive, tape-measure-based body fat estimate following the standardized US Navy method. It is ideal when DEXA or caliper data is unavailable and the user can provide neck, waist, and (for women) hip circumference measurements. Prefer this over BMI for body composition analysis since it differentiates fat from lean mass. Also suited for military or occupational fitness assessments that specifically reference the Navy formula.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-29T13:11:22.136Z","isFirstParty":false,"canonicalSlug":"us-navy-body-fat-percentage-calculator-f900b166"}