⚖️BMI Calculator
Calculate Body Mass Index from weight (kg) and height (cm), with the WHO weight category and the healthy BMI weight range for your height.
Worked examples
70 kg, 175 cm
GET /api/v1/calculators/bmi-calculator?weight=70&height=175
Result: 22.86
55 kg, 160 cm
GET /api/v1/calculators/bmi-calculator?weight=55&height=160
Result: 21.48
95 kg, 180 cm
GET /api/v1/calculators/bmi-calculator?weight=95&height=180
Result: 29.32
Machine API (x402)
$0.001 / callThis tool is also a JSON API for AI agents. Requests without payment receive 402 Payment Required plus instructions; agents pay USDC on Base via the x402 protocol — no accounts, no API keys.
GET /api/v1/calculators/bmi-calculator?weight=70&height=175 HTTP/1.1
Host: agenttools-hub.vercel.app
→ 402 (payment required, instructions in headers)
→ 200 (after X-PAYMENT header; JSON body below)
{
"tool": "calculators/bmi-calculator",
"input": {"weight":70,"height":175},
"result": { "value": 22.857143, "answer": "22.86" }
}Agent docs: /llms.txt · OpenAPI spec · integration guide
About this tool
Body Mass Index divides your weight in kilograms by the square of your height in meters. The result is mapped to the standard WHO categories, and the healthy weight range for your exact height is shown.
BMI = weight (kg) ÷ height² (m²)
Frequently asked questions
What is a healthy BMI?
The WHO classifies 18.5–24.9 as healthy weight, below 18.5 as underweight, 25–29.9 as overweight and 30+ as obesity.
Is BMI accurate for athletes?
No. BMI does not distinguish muscle from fat, so muscular people can score 'overweight' while being healthy. It is a population screening tool, not a diagnosis.
Does BMI work for children?
Children and teens are assessed with age- and sex-specific percentile charts instead of the adult ranges used here.