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API · /bmi-api

BMI & Body Composition API

healthy 3,780 Subscribers

Body-composition maths as an API, computed locally and deterministically. The bmi endpoint computes the body mass index, BMI = weight/height², classifies it on the WHO scale (underweight, normal, overweight, obese) and returns the healthy weight range for the person's height. The idealweight endpoint computes the ideal body weight by the four classic formulas — Devine, Robinson, Miller and Hamwi — each a base weight plus an increment for every inch of height above five feet, and their average. The bodyfat endpoint estimates body-fat percentage by the US Navy circumference method from the neck and waist (and hip for women) and the height, classifies it from essential to high, and — given a weight — splits it into fat mass and lean mass. Everything is computed locally and deterministically, so it is instant and private. Ideal for fitness, health and wellness app developers, body-tracking and coaching tools, gym and clinic dashboards, and self-assessment apps. Pure local computation — no key, no third-party service, instant. Live, nothing stored. Estimates only, not medical advice. 3 endpoints. This is body composition; for basal metabolic rate and calories use a BMR API.

#bmi #body-composition #body-fat #ideal-weight #fitness #developer-tools
api.oanor.com/bmi-api
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Machine-readable spec so AI agents can integrate this API.

/api/bmi-api/openapi.json
/api/bmi-api/llms.txt

Discovery: GET /api/index.json lists every API.

API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
95 ms
Server probes · 24h
Subscribers
3,780
active
Total calls
32
last 7 days
status Full status page → · 24 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 3,000 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • 3,000 BMI calculations/month
  • WHO BMI classification bands
  • Metric & imperial units
  • Community support
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Starter

€4.00 /month

  • 40,000 calls / month
  • 5 requests / second
  • Hard cap (429 above quota, no overage)
  • 40,000 calls/month
  • BMI + ideal-weight endpoints
  • Body-fat % estimation
  • Email support
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Pro

€12.00 /month

  • 250,000 calls / month
  • 15 requests / second
  • Hard cap (429 above quota, no overage)
  • 250,000 calls/month
  • Full body-composition suite (BMI, body-fat, ideal weight)
  • Age & sex-adjusted classification
  • Priority email support
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Mega

€39.00 /month

  • 1,500,000 calls / month
  • 40 requests / second
  • Hard cap (429 above quota, no overage)
  • 1,500,000 calls/month
  • All composition endpoints, deterministic results
  • Bulk-friendly high RPS for fitness apps
  • 99.9% uptime SLA & priority support
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Related APIs

Other APIs with overlapping tags.

Health Calculator API

A complete health & fitness calculator suite in one API: Body Mass Index with category and healthy-weight range, Basal Metabolic Rate (Mifflin-St Jeor and Harris-Benedict), Total Daily Energy Expenditure with weight-loss/gain calorie targets, macronutrient splits (balanced, low-carb, high-protein, keto, endurance) with fibre, U.S. Navy body-fat percentage, ideal body weight across four classic formulas (Devine, Robinson, Miller, Hamwi), and daily water intake. Every endpoint accepts GET query parameters or a JSON POST body and works in both metric and imperial units. All computation is done locally with established public-domain equations, so responses are instant and the service is always available. Ideal for fitness trackers, nutrition apps, telehealth and wellness dashboards.

api.oanor.com/healthcalc-api

Body Fat API

Body-fat-percentage and body-composition maths as an API, computed locally and deterministically. The navy endpoint applies the US Navy circumference method — for men %BF = 495/(1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450, and for women a formula that adds the hip measurement — to estimate body fat from a tape measure alone, returning the percentage and the fitness category (essential, athletes, fitness, acceptable or obese); a man of 178 cm with a 40 cm neck and 90 cm waist reads about 18.7 %. The deurenberg endpoint gives the BMI-based estimate %BF = 1.20·BMI + 0.23·age − 10.8·(1 if male) − 5.4 from BMI or weight and height plus age. The composition endpoint splits a total weight into fat mass and lean (fat-free) mass from a body-fat percentage. Circumferences and height are in centimetres and weight in kilograms. Everything is computed locally and deterministically, so it is instant and private. Ideal for fitness, wellness, gym, nutrition, body-tracking and health-education app developers, body-composition and progress-tracking tools, and coaching software. These are estimation formulas, not a substitute for DEXA or professional assessment. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is body-fat percentage; for body-mass index use a BMI API and for basal metabolic rate a BMR API.

api.oanor.com/bodyfat-api

Barbell & Lifting API

Barbell and weight-training maths as an API, computed locally and deterministically — the plate-loading and percentage numbers a lifter, coach or gym app works out at the rack. The plates endpoint solves the everyday gym puzzle of which plates go on each side for a target weight: 100 kg on a standard 20 kg bar means 40 kg a side, loaded heaviest first as a 25 and a 15; 102.5 kg adds the 1.25 micro-plate; and if a target is not reachable with the plates on hand it loads the closest it can and tells you the shortfall, so you never guess. It works in kilograms or pounds (225 lb on a 45 lb bar is two 45s a side), with a custom bar weight and a custom plate set. The percent endpoint turns a one-rep-max into the working weight you actually load: 80 % of a 100 kg max is 80 kg, and asking for a five-rep weight returns about 85.7 kg via the Epley formula (1RM = weight × (1 + reps ÷ 30)) — five reps sits near 86 % of max, ten reps near 75 %. The warmup endpoint builds a ramp from the empty bar to the working set at roughly 40, 55, 70 and 85 %, each rounded to a loadable increment, with the rep count dropping as the bar gets heavy. Everything is computed locally and deterministically, so it is instant and private. Ideal for gym, strength-training, powerlifting and fitness app developers, workout-logger and coaching tools, and smart-rack and plate-calculator builders. Pure local computation — no key, no third-party service, instant. Exact maths, no simulation. Live, nothing stored. 3 compute endpoints. For one-rep-max estimation from a set use a strength API.

api.oanor.com/barbell-api

Calorie Burn API

Exercise calorie-burn maths as an API, computed locally and deterministically with the MET (metabolic-equivalent) method. The activity endpoint computes the calories burned by an activity, calories = MET × weight × hours, taking the MET value directly or from a named-activity table (walking, running, cycling, swimming, HIIT, rowing, yoga, weightlifting and more), and returns the calories per minute. The steps endpoint turns a step count into distance and calories: the stride is estimated from height (about 0.415 × height for walking, 0.65 for running), the distance is steps × stride, and the energy is the distance times bodyweight times a net cost of roughly 0.5 kcal/kg/km walking or 1.0 running. The duration endpoint works backwards, giving the minutes of an activity needed to burn a target number of calories. Everything is computed locally and deterministically, so it is instant and private. Ideal for fitness, activity-tracking and weight-management app developers, workout and step-counter tools, and wellness dashboards. Pure local computation — no key, no third-party service, instant. Live, nothing stored. Estimates only. 3 endpoints. This is activity energy expenditure; for resting metabolism and TDEE use a BMR API.

api.oanor.com/calorieburn-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for BMI & Body Composition API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call BMI & Body Composition API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for BMI & Body Composition API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does BMI & Body Composition API cost?
BMI & Body Composition API has a free tier with 100 calls / month. Paid plans start at €4.00 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is BMI & Body Composition API GDPR-compliant?
All requests to BMI & Body Composition API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.

Pick an endpoint from the list on the left to see its details and try it.

Code snippets

Sign up to get an API key, then call any path under your slug.

curl https://api.oanor.com/bmi-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/bmi-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/bmi-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);
import requests
r = requests.get(
    "https://api.oanor.com/bmi-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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