Body Mass Index calculator API

Compute Body Mass Index (BMI = weight(kg) / height(m)^2) with WHO category bands and the healthy-weight range for the given height — deterministic arithmetic LLMs slip on. Answers 'what's my BMI', 'am I overweight at 80kg/180cm', 'healthy weight range for my height', 'BMI category'.

Price$0.01per request

MethodPOST

Route/v1/health/bmi

StatusLive

MIME typeapplication/json

Rate limit120/minute

CacheNo cache

healthbmibody-mass-indexweightfitnessobesitywhocalculator

API URLhttps://x402.hexl.dev/v1/health/bmi

Integration docs

Example request

{
  "weightKg": 80,
  "heightCm": 180
}

Example response

{
  "bmi": 24.7,
  "category": "normal",
  "formula": "BMI = weightKg / heightM^2",
  "inputs": {
    "weightKg": 80,
    "heightCm": 180,
    "heightM": 1.8
  },
  "healthyWeightRangeKg": {
    "min": 59.9,
    "max": 80.7
  }
}

Input schema

{
  "type": "object",
  "required": [
    "weightKg",
    "heightCm"
  ],
  "properties": {
    "weightKg": {
      "type": "number",
      "description": "Body weight in kilograms",
      "examples": [
        80
      ]
    },
    "heightCm": {
      "type": "number",
      "description": "Height in centimetres",
      "examples": [
        180
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}