Overview
BMI Calculator uses the Mifflin-St Jeor equation for accurate BMR calculations and evidence-based activity multipliers for TDEE. It provides actionable data for fitness apps, health trackers, and nutrition planning tools.
Live Test BMI Calculator API →
Endpoint
One host, one path per API. The block below shows this call in four languages; every one of them is the same HTTP request. Making requests covers the timeouts, retries and parameter rules that apply to all of them. The SDKs wrap the same call in a typed client.
curl "https://api.apiverve.com/v1/bmicalculator?weight=180&height=70&unit=imperial&age=30&gender=male&activityLevel=moderate" \
-H "x-api-key: your_api_key_here"const res = await fetch('https://api.apiverve.com/v1/bmicalculator?weight=180&height=70&unit=imperial&age=30&gender=male&activityLevel=moderate', {
headers: { 'x-api-key': 'your_api_key_here' },
});
if (!res.ok) throw new Error(`${res.status} ${await res.text()}`);
const { data } = await res.json();
console.log(data);import requests
res = requests.get(
"https://api.apiverve.com/v1/bmicalculator?weight=180&height=70&unit=imperial&age=30&gender=male&activityLevel=moderate",
headers={"x-api-key": "your_api_key_here"},
timeout=15,
)
res.raise_for_status()
print(res.json()["data"])package main
import (
"fmt"
"io"
"net/http"
)
func main() {
req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/bmicalculator?weight=180&height=70&unit=imperial&age=30&gender=male&activityLevel=moderate", nil)
req.Header.Set("x-api-key", "your_api_key_here")
res, err := http.DefaultClient.Do(req)
if err != nil {
panic(err)
}
defer res.Body.Close()
out, _ := io.ReadAll(res.Body)
fmt.Println(string(out))
}Replace your_api_key_here with the key from your dashboard. When the inputs arrive as a list rather than one at a time, batch requests run up to 200 of them through this same API in a single call.
Authentication
Send your key in the x-api-key header. That is the only auth step — there is no token exchange and no per-endpoint scope to configure. Authentication covers creating, rotating and revoking keys.
A 401 means the key is missing, invalid or expired. A 403 means the key is valid but not permitted here — blocked by a key restriction or an IP allow-list. Running out of credits is a 429.
Parameters
Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them.
| Parameter | Type | Description |
|---|---|---|
weightRequired | number | Weight in kg (metric) or lbs (imperial) range 1–∞ |
heightRequired | number | Height in cm (metric) or inches (imperial) range 1–∞ |
unitRequired | string | Unit system for weight and heightmetricimperial |
ageOptional | number | Age in years (required for BMR/TDEE calculations) range 1–120 |
genderOptional | string | Gender (required for BMR/TDEE calculations)malefemale |
activityLevelOptional | string | Activity level (required for TDEE/calorie calculations)sedentarylightmoderateactiveveryactive |
Response
Every API returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape. Response format covers the envelope, the other output formats and how premium fields are withheld.
{
"status": "ok",
"error": null,
"data": {
"height": "70 inches",
"weight": "180 lbs",
"bmi": 25.83,
"bmiPrime": 1.033,
"category": "Overweight",
"risk": "Increased risk",
"summary": "BMI is above the healthy range. Lifestyle changes may be beneficial.",
"idealWeightRange": {
"min": 129,
"max": 173.5,
"unit": "lbs"
},
"weightToChange": {
"direction": "lose",
"amount": 6.5,
"unit": "lbs"
},
"bmr": 1783,
"tdee": 2763,
"calorieTargets": {
"extremeDeficit": 1763,
"moderateDeficit": 2263,
"maintain": 2763,
"moderateSurplus": 3063,
"bulkSurplus": 3263
},
"macros": {
"lose": {
"protein": 198,
"carbs": 198,
"fat": 75
},
"maintain": {
"protein": 207,
"carbs": 276,
"fat": 92
},
"gain": {
"protein": 230,
"carbs": 345,
"fat": 85
}
}
}
}
Response fields
Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.
| Field | Type | Example | Description |
|---|---|---|---|
height | string | "70 inches" | Formatted height with unit |
weight | string | "180 lbs" | Formatted weight with unit |
bmi | number | 25.83 | Calculated Body Mass Index |
bmiPrimePremium | number | 1.033 | Ratio of BMI to upper normal limit (25). Values <1 are normal weight. |
category | string | "Overweight" | BMI category (Underweight, Normal, Overweight, Obese Class I/II/III) |
riskPremium | string | "Increased risk" | Health risk level based on BMI category |
summaryPremium | string | "BMI is above the healthy range. Lifestyle changes may be beneficial." | Brief interpretation of BMI results |
idealWeightRange | object | {...} | Healthy weight range for this height (min, max, unit) |
min | number | 129 | Lowest weight in the healthy BMI range |
max | number | 173.5 | Highest weight in the healthy BMI range |
unit | string | "lbs" | Unit the ideal weight range is expressed in (lbs or kg) |
weightToChangePremium | object | {...} | Weight to lose or gain to reach normal BMI (direction, amount, unit) |
directionPremium | string | "lose" | Whether weight needs to be lost, gained, or maintained |
amountPremium | number | 6.5 | How much weight to lose or gain to reach the healthy range |
unitPremium | string | "lbs" | Unit the weight change is expressed in (lbs or kg) |
bmrPremium | number | 1783 | Basal Metabolic Rate - calories burned at rest (requires age, gender) |
tdeePremium | number | 2763 | Total Daily Energy Expenditure - calories burned per day (requires age, gender, activityLevel) |
calorieTargetsPremium | object | {...} | Daily calorie targets for different goals (extremeDeficit, moderateDeficit, maintain, moderateSurplus, bulkSurplus) |
extremeDeficitPremium | number | 1763 | Daily calories for aggressive weight loss, roughly 1000 below maintenance |
moderateDeficitPremium | number | 2263 | Daily calories for steady weight loss, roughly 500 below maintenance |
maintainPremium | number | 2763 | Daily calories to hold current weight, equal to total daily energy expenditure |
moderateSurplusPremium | number | 3063 | Daily calories for lean weight gain, roughly 300 above maintenance |
bulkSurplusPremium | number | 3263 | Daily calories for faster weight gain, roughly 500 above maintenance |
macrosPremium | object | {...} | Macronutrient targets in grams (protein, carbs, fat) for lose/maintain/gain goals |
losePremium | object | {...} | Daily macronutrient grams for the weight loss calorie target |
proteinPremium | number | 198 | Grams of protein per day while losing weight |
carbsPremium | number | 198 | Grams of carbohydrate per day while losing weight |
fatPremium | number | 75 | Grams of fat per day while losing weight |
maintainPremium | object | {...} | Daily macronutrient grams for the maintenance calorie target |
proteinPremium | number | 207 | Grams of protein per day at maintenance |
carbsPremium | number | 276 | Grams of carbohydrate per day at maintenance |
fatPremium | number | 92 | Grams of fat per day at maintenance |
gainPremium | object | {...} | Daily macronutrient grams for the weight gain calorie target |
proteinPremium | number | 230 | Grams of protein per day while gaining weight |
carbsPremium | number | 345 | Grams of carbohydrate per day while gaining weight |
fatPremium | number | 85 | Grams of fat per day while gaining weight |
Errors
Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change. Error handling covers the full status list and which of them are worth retrying.
| Status | Meaning | What to do |
|---|---|---|
400 | Input was rejected | Read error; it names the parameter. |
401 | Key missing or invalid | Check the header name and the key value. |
403 | Key valid, but not permitted | A key restriction or IP allow-list; see key scoping. |
429 | Rate limited, or out of credits | Read error to tell them apart; see rate limits. |
Use cases
- Fitness Apps
- Calculate BMI, BMR, TDEE and macro targets for users tracking their fitness journey.
- Health Tracking
- Provide users with their ideal weight range and how much to gain or lose to reach a healthy BMI.
- Nutrition Planning
- Generate personalized calorie and macronutrient targets for meal planning applications.
- Weight Loss Programs
- Calculate calorie deficits and protein targets for weight loss applications.
Other ways to use BMI Calculator
Set up BMI Calculator on APIVerve, or reach the same source a different way. Your APIVerve account and credits work on all of them — one key, one balance.
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