Fitness and Body Calculators
Estimated maximum heart rate (Tanaka, Fox) and five training zones as percent of max or by heart-rate reserve (Karvonen).
OtherLiveeip155:8453Exactvia cdp
Heart-rateTrainingZonesRunning
Calls · 30d
1
This endpoint's own trailing-30-day call count, as published by the upstream catalog and snapshotted daily. 4 snapshots so far.
$24.31
Verified settled volume
1,175 settlements proven x402 by their on-chain EIP-3009 marker.
$0.020
Listed price
As published in the catalog. Always read the live 402 before paying.
1
Calls · 30d
Upstream's own call count for this endpoint, not ours.
1
Unique payers · 30d
Last called 2026-10-20 20:46Z
—
Upstream on-chain volume
Reported by the source catalog.
Paid to
0xb531320805C5BED1D46AEaDcF4F008FDF172DBDaThe wallet the 402 directs payment to. Its whole payment record — every payer, every chain — is on the merchant page.
Asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
Provider
The payTo wallet does not resolve to a registered ERC-8004 agent. That is not a verdict on the service — most of the catalog is unregistered.
Live 402 challenge
Captured by the enrichment pass, not read just now. Prices can change — always read the 402 the endpoint answers with.
{
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"scheme": "exact",
"network": "base",
"mimeType": "application/json",
"resource": "https://fitness-calc.x402tookit.com/heart-rate-zones",
"description": "Estimated maximum heart rate (Tanaka, Fox) and five training zones as percent of max or by heart-rate reserve (Karvonen).",
"outputSchema": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {
"age": 40,
"restingHr": 60
}
},
"output": {
"age": 40,
"asOf": "2026-10-11T08:36:50.345Z",
"zones": [
{
"bpm": {
"max": 132,
"min": 120
},
"zone": "Zone 1 recovery",
"percentOfReserve": "50-60%"
},
{
"bpm": {
"max": 144,
"min": 132
},
"zone": "Zone 2 endurance base",
"percentOfReserve": "60-70%"
}
],
"method": "Karvonen heart-rate reserve",
"source": "computed locally",
"reasons": [
"Tanaka (2001): 208 - 0.7 x age, better for adults over 40 than Fox 220 - age.",
"Karvonen: resting + percent x (max - resting).",
"…1 more"
],
"reserve": 120,
"summary": "Max heart rate 180 bpm (Tanaka; Fox gives 180); Karvonen reserve zones: 120-132, 132-144, 144-156, 156-168, 168-180 bpm.",
"verdict": "COMPUTED",
"degraded": false,
"maxHrFox": 180,
"maxHrUsed": 180,
"restingHr": 60,
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
"notChecked": [
"individual variation (the age formulas have a spread of about +/-10 beats per minute)",
"medications such as beta blockers that lower heart rate",
"…1 more"
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"description": "Estimated maximum heart rate (Tanaka, Fox) and five training zones as percent of max or by heart-rate reserve (Karvonen).",
"outputSchema": {
"input": {
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"queryParams": {
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"asOf": "2026-10-11T08:36:50.345Z",
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"min": 120
},
"zone": "Zone 1 recovery",
"percentOfReserve": "50-60%"
},
{
"bpm": {
"max": 144,
"min": 132
},
"zone": "Zone 2 endurance base",
"percentOfReserve": "60-70%"
}
],
"method": "Karvonen heart-rate reserve",
"source": "computed locally",
"reasons": [
"Tanaka (2001): 208 - 0.7 x age, better for adults over 40 than Fox 220 - age.",
"Karvonen: resting + percent x (max - resting).",
"…1 more"
],
"reserve": 120,
"summary": "Max heart rate 180 bpm (Tanaka; Fox gives 180); Karvonen reserve zones: 120-132, 132-144, 144-156, 156-168, 168-180 bpm.",
"verdict": "COMPUTED",
"degraded": false,
"maxHrFox": 180,
"maxHrUsed": 180,
"restingHr": 60,
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
"notChecked": [
"individual variation (the age formulas have a spread of about +/-10 beats per minute)",
"medications such as beta blockers that lower heart rate",
"…1 more"
],
"maxHrTanaka": 180,
"maxHrMeasured": null
}
},
"maxAmountRequired": "20000",
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},
{
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"payTo": "0xb531320805C5BED1D46AEaDcF4F008FDF172DBDa",
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"mimeType": "application/json",
"resource": "https://fitness-calc.x402tookit.com/heart-rate-zones",
"description": "Estimated maximum heart rate (Tanaka, Fox) and five training zones as percent of max or by heart-rate reserve (Karvonen).",
"outputSchema": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {
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"restingHr": 60
}
},
"output": {
"age": 40,
"asOf": "2026-10-11T08:36:50.345Z",
"zones": [
{
"bpm": {
"max": 132,
"min": 120
},
"zone": "Zone 1 recovery",
"percentOfReserve": "50-60%"
},
{
"bpm": {
"max": 144,
"min": 132
},
"zone": "Zone 2 endurance base",
"percentOfReserve": "60-70%"
}
],
"method": "Karvonen heart-rate reserve",
"source": "computed locally",
"reasons": [
"Tanaka (2001): 208 - 0.7 x age, better for adults over 40 than Fox 220 - age.",
"Karvonen: resting + percent x (max - resting).",
"…1 more"
],
"reserve": 120,
"summary": "Max heart rate 180 bpm (Tanaka; Fox gives 180); Karvonen reserve zones: 120-132, 132-144, 144-156, 156-168, 168-180 bpm.",
"verdict": "COMPUTED",
"degraded": false,
"maxHrFox": 180,
"maxHrUsed": 180,
"restingHr": 60,
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
"notChecked": [
"individual variation (the age formulas have a spread of about +/-10 beats per minute)",
"medications such as beta blockers that lower heart rate",
"…1 more"
],
"maxHrTanaka": 180,
"maxHrMeasured": null
}
},
"maxAmountRequired": "20000",
"maxTimeoutSeconds": 300
}
],
"x402Version": 1,
"alsoAvailable": {
"llms": "https://fitness-calc.x402tookit.com/llms.txt",
"catalog": "https://fitness-calc.x402tookit.com/catalog",
"message": "Fitness and Body Calculators has 10 pay-per-call endpoints (BMI, ideal weight, calorie needs, macros, one-rep max, heart-rate zones, race pace and prediction, body fat, calorie burn, due date.), from $0.02 a call. See the full menu and send your agents our way.",
"openapi": "https://fitness-calc.x402tookit.com/openapi.json",
"related": [
{
"url": "https://fitness-calc.x402tookit.com/pace-race",
"path": "/pace-race",
"what": "Running pace per km and per mile, speed, and predicted times for other race distances usi…",
"price": "$0.02"
},
{
"url": "https://fitness-calc.x402tookit.com/ideal-weight",
"path": "/ideal-weight",
"what": "Ideal body weight by the Devine, Robinson, Miller and Hamwi formulas from height and sex,…",
"price": "$0.02"
},
{
"url": "https://fitness-calc.x402tookit.com/macro-split",
"path": "/macro-split",
"what": "Protein, carbohydrate and fat grams for a calorie target from a preset or your own percen…",
"price": "$0.02"
}
]
}
}Accepts
The payment requirements as published to the catalog. Read the live 402 before paying — a price here is a claim, not a quote.
0.02USDC≈ $0.02 USD
on Base · exact scheme
Pay 0.02 USDC on Base to 0xb531…2DBDa. The signed payment is good for 5 minutes.
- Paid to
- 0xb531…2DBDa
- USD Coin contract
- 0x8335…02913
- Payment window
- 5 minutes
- As published
- 20000 smallest units
20000units
on solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp · exact scheme
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- DUPiup…eEm8s
- Token contract
- EPjFWd…TDt1v
- Payment window
- 5 minutes
20000units
on Polygon · exact scheme
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- 0xb531…2DBDa
- Token contract
- 0x3c49…c3359
- Payment window
- 5 minutes
20000units
on Arbitrum · exact scheme
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- 0xb531…2DBDa
- Token contract
- 0xaf88…e5831
- Payment window
- 5 minutes
The catalog’s raw entry
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{
"bazaar": {
"info": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {
"age": 40,
"restingHr": 60
}
},
"output": {
"type": "json",
"example": {
"age": 40,
"asOf": "2026-10-11T08:36:50.345Z",
"zones": [
{
"bpm": {
"max": 132,
"min": 120
},
"zone": "Zone 1 recovery",
"percentOfReserve": "50-60%"
},
{
"bpm": {
"max": 144,
"min": 132
},
"zone": "Zone 2 endurance base",
"percentOfReserve": "60-70%"
}
],
"method": "Karvonen heart-rate reserve",
"source": "computed locally",
"reasons": [
"Tanaka (2001): 208 - 0.7 x age, better for adults over 40 than Fox 220 - age.",
"Karvonen: resting + percent x (max - resting).",
"…1 more"
],
"reserve": 120,
"summary": "Max heart rate 180 bpm (Tanaka; Fox gives 180); Karvonen reserve zones: 120-132, 132-144, 144-156, 156-168, 168-180 bpm.",
"verdict": "COMPUTED",
"degraded": false,
"maxHrFox": 180,
"maxHrUsed": 180,
"restingHr": 60,
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
"notChecked": [
"individual variation (the age formulas have a spread of about +/-10 beats per minute)",
"medications such as beta blockers that lower heart rate",
"…1 more"
],
"maxHrTanaka": 180,
"maxHrMeasured": null
}
}
},
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],
"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
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"zones": {
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"null"
],
"items": {
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"bpm": {
"type": [
"null",
"object"
],
"properties": {
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"null",
"number"
]
},
"min": {
"type": [
"null",
"number"
]
}
}
},
"zone": {
"type": [
"null",
"string"
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},
"percentOfReserve": {
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"null",
"string"
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}
},
"method": {
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"string"
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},
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"string"
]
},
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],
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},
"reserve": {
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"summary": {
"type": [
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},
"verdict": {
"type": [
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"string"
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},
"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": {
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}
},
"maxHrTanaka": {
"type": [
"null",
"number"
]
},
"maxHrMeasured": {}
}
}
}
}
}
}
}
}Provenance
- Seen in the source catalog
- 2026-10-20 20:46Z
- Last indexed by Roundhouse
- 2026-10-22 06:50Z
- Last enriched (probe, favicon, geo)
- 2026-10-20 22:45Z
- x402 version
- 2
- Max timeout
- 300s
- Liveness probe
- HTTP 402
Hand this page to an agent
Copy the prompt and paste it into Claude, an MCP client or your own agent — it will vet this service and call it over the free read API. No key, no account.
GET api.roundhouseai.io/v0/endpoints
This endpoint's own trailing-30-day call count, as published by the upstream catalog and snapshotted daily. 4 snapshots so far. Verified volume counts only settlements with an on-chain EIP-3009 marker.
Show the promptHide the prompt
Using Roundhouse, look up the x402 service Fitness and Body Calculators and tell me whether it is worth paying: what a call costs, whether the endpoint answered when last probed, and what its payment record actually shows. curl -s 'https://api.roundhouseai.io/v0/endpoints?q=Fitness%20and%20Body%20Calculators' curl -s 'https://api.roundhouseai.io/v0/merchants/<the payTo wallet returned above>' Then call it: read the price from the live 402 at https://fitness-calc.x402tookit.com/heart-rate-zones, never from a cached figure, and pay with an x402 client. The /v0 API needs an API key (`authorization: Bearer rh_live_…`) on everything except /v0/unified* and /v0/endpoints. Either pay over x402 (mint a personal key for $0.01 at GET https://api.roundhouseai.io/v0/test/x402), or ask me for an organization key, which I create at https://roundhouseai.io/dashboard/connections. If you have neither, ask before going further. If you do not have Roundhouse tools or skills installed, read https://roundhouseai.io/skill.md first — it is the whole procedure.