{"uid":"cap_qZxbmXPuUBueHWoCl8hGA","slug":"heart-rate-zones-calculator-ee20a4fc","name":"Heart Rate Zones Calculator","description":"Estimated maximum heart rate (Tanaka, Fox) and five training zones as percent of max or by heart-rate reserve (Karvonen).","url":"https://fitness-calc.x402tookit.com/heart-rate-zones?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":["age"],"properties":{"age":{"type":"number","description":"Age in years, 10 to 100"},"maxHr":{"type":"number","description":"Your measured maximum, if you have one"},"restingHr":{"type":"number","description":"Resting heart rate in bpm for the Karvonen reserve method"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"age":{"type":["null","number"]},"asOf":{"type":["null","string"]},"zones":{"type":["array","null"],"items":{"type":"object","properties":{"bpm":{"type":["null","object"],"properties":{"max":{"type":["null","number"]},"min":{"type":["null","number"]}}},"zone":{"type":["null","string"]},"percentOfReserve":{"type":["null","string"]}}}},"method":{"type":["null","string"]},"source":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"reserve":{"type":["null","number"]},"summary":{"type":["null","string"]},"verdict":{"type":["null","string"]},"degraded":{"type":["boolean","null"]},"maxHrFox":{"type":["null","number"]},"maxHrUsed":{"type":["null","number"]},"restingHr":{"type":["null","number"]},"disclaimer":{"type":["null","string"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"maxHrTanaka":{"type":["null","number"]},"maxHrMeasured":{}}}}}}},"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_rq1-CBH-84mCG1AlEcxUw","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":"Calculates estimated maximum heart rate (Tanaka and Fox formulas) and five training zones by percentage of max or heart-rate reserve (Karvonen method) from age and optional resting HR.","exampleAgentPrompt":"I'm 38 years old with a resting heart rate of 58 bpm — can you calculate my five heart rate training zones using the Karvonen method?","exampleUseCases":[{"title":"Zone 2 cardio training plan","prompt":"I'm 45 years old and want to train in zone 2 for endurance — what heart rate range should I stay in?"},{"title":"Athlete with measured max HR","prompt":"My measured max heart rate is 187 bpm and I'm 31 — can you calculate my five training zones using that actual number instead of an estimate?"},{"title":"Beginner learning training zones","prompt":"I'm 55 years old with a resting heart rate of 65 bpm, just starting to exercise — can you show me all five heart rate zones using the Karvonen reserve method so I know what bpm to target?"}],"resultDescription":"Returns both Tanaka and Fox estimated maximum heart rates, the max HR actually used in calculations, resting HR and heart rate reserve (if provided), five labeled training zones each with a bpm min/max range and percent-of-reserve values, the calculation method name, a summary, verdict, disclaimer, and any degraded-mode flags or reasons.","failureModes":["Age outside valid range (10–100) returns an error or degraded result","Missing required 'age' parameter causes a 400-level error","Providing a physiologically implausible measured max HR may trigger a warning or degraded flag","Resting HR provided without age still requires age as the required field"],"whenToPreferThis":"Choose this endpoint when you need structured, formula-attributed heart rate zone data (Tanaka, Fox, Karvonen) with per-zone bpm ranges rather than a generic static chart. Ideal when the user supplies their resting HR for the more precise Karvonen/reserve method, or when you need to compare estimated vs measured max HR in one call.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-30T00:34:50.209Z","isFirstParty":false,"canonicalSlug":"heart-rate-zones-calculator-ee20a4fc"}