# BMI Calculator with WHO Category and Healthy Weight Range

> BMI Calculator with WHO Category and Healthy Weight Range is a paid API for AI agents from fitness-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-31).

Calculates body mass index from weight and height (metric or imperial), returns the WHO adult category, and the healthy weight range for normal BMI (18.5–24.9).

## Facts

- Endpoint: GET https://fitness-calc.x402tookit.com/bmi?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/bmi-calculator-with-who-category-and-healthy-weight-range-fc320922
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_CFBDcQQEnUSOKpJjmVltt

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability bmi-calculator-with-who-category-and-healthy-weight-range-fc320922
```

Example prompt: Can you calculate my BMI? I weigh 185 pounds and I'm 5 feet 11 inches tall — also tell me what WHO category I fall into and how far I am from a healthy weight.

## When to prefer this

Choose this endpoint when you need a quick, standards-based BMI calculation with a WHO category label and healthy weight range targets — especially useful for fitness apps, health screening workflows, or coaching agents that need to advise users on weight goals. Supports both metric and imperial inputs natively, making it versatile for US and international users without manual unit conversion.

## Known failure modes

- Missing required weight parameter returns an error
- Invalid or negative weight/height values may return null BMI
- Non-numeric input for weight or height causes a validation failure
- Units mismatch (e.g. passing kg weight with imperial flag) may produce implausible results
- BMI categories are for adults 20+; results may include a note when age is below 20

## How this service works

Body mass index from weight and height, metric or imperial, with the WHO adult category and the 18.5 to 24.9 weight range.

## Output

Returns the computed BMI value (number), the WHO adult category (e.g. Underweight, Normal weight, Overweight, Obese), normalized height in cm and weight in kg, the healthy weight range for BMI 18.5–24.9 in both kg and lb, how many kg to gain or lose to reach the normal range boundaries, a plain-language summary, and an optional disclaimer. Also includes a data source and timestamp.

## Request schema (JSON Schema)

```json
{
 "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": [
      "weight"
     ],
     "properties": {
      "age": {
       "type": "number",
       "description": "Age in years (BMI categories apply to adults 20 and over)"
      },
      "units": {
       "type": "string",
       "description": "metric (default: kg and cm) or imperial (lb, feet and inches)"
      },
      "height": {
       "type": "number",
       "description": "Height in cm (metric)"
      },
      "weight": {
       "type": "number",
       "description": "Weight in kg, or pounds if units=imperial"
      },
      "heightFt": {
       "type": "number",
       "description": "Feet (imperial)"
      },
      "heightIn": {
       "type": "number",
       "description": "Inches (imperial; total inches if heightFt is omitted)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "bmi": {
       "type": [
        "null",
        "number"
       ]
      },
      "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"
       ]
      },
      "heightCm": {
       "type": [
        "null",
        "number"
       ]
      },
      "weightKg": {
       "type": [
        "null",
        "number"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "arra
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/bmi-calculator-with-who-category-and-healthy-weight-range-fc320922/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fitness-calc.x402tookit.com](https://www.zero.xyz/host/fitness-calc.x402tookit.com/llms.txt)