# BodyMassIndex.app

> Free multilingual ideal weight and BMI calculator. Instant results using four evidence-based clinical formulas (Devine 1974, Robinson 1983, Miller 1983, BMI-22 target), WHO healthy weight ranges, and height percentile statistics. Covers women and men, heights 140–220 cm (4 ft 10 in – 7 ft 3 in), in English, Spanish, and Russian.

## Ideal Weight Calculators

The core section of the site. Each page provides ideal weight results from multiple formulas, a healthy BMI range (18.5–24.9), and a reference table.

- [Ideal Weight Overview — Women & Men](/ideal-weight/) — Universal calculator with formula history, comparison table at 170 cm, and Devine reference table for 165–180 cm
- [Ideal Weight for Women](/ideal-weight/female/) — Women-specific calculator and reference table
- [Ideal Weight for Men](/ideal-weight/male/) — Men-specific calculator and reference table
- [Example: Ideal Weight for a 165 cm Woman](/ideal-weight/female/165cm) — Full detail page: 4 formula results, worked equations, WHO BMI categories with weight thresholds, height percentile statistics
- [Example: Ideal Weight for a 178 cm Man](/ideal-weight/male/178cm) — Same detail format for men
- [Ideal Weight for Women by Height (Spanish)](/es/peso-ideal/mujer/) — Spanish version
- [Ideal Weight for Men by Height (Spanish)](/es/peso-ideal/hombre/) — Spanish version

## BMI Calculator

- [BMI Calculator — Home](/): Calculate Body Mass Index from height and weight. Shows result, WHO category (Severe Thinness through Obese Class III), and a link to the matching ideal weight page.

## BMI Calculator for Kids (WHO Growth Standards)

Children's BMI cannot be interpreted with adult thresholds. This calculator uses age- and sex-specific WHO Child Growth Standard SD reference tables (8 lookup tables: 4 age groups × 2 sexes).

- [BMI for Kids — English](/bmi-for-kids/)
- [IMC para Niños — Spanish](/es/imc-ninos/)
- [ИМТ для детей — Russian](/ru/bmi-for-kids/)

**Age groups and indexing:**
- Newborns 0–13 weeks: row = week number (0–13)
- Babies 0–2 years: row = years × 12 + months (0–24)
- Children 2–5 years: row = (years × 12 + months) − 24 (0–36)
- Children 5–19 years: row = (years × 12 + months) − 60 (0–167)

**Calculation formulas:**
- BMI = weight_kg / (height_m)²
- Classification: ≤ −3SD severe underweight → −1SD to +1SD normal → ≥ +3SD severely obese
- Normal weight range: (−1SD value) × height_m² to (+1SD value) × height_m²
- Body fat %: 1.51 × BMI − 0.70 × age_years − 3.6 × sex (1=boy, 0=girl) + 1.4
- Daily water (L): weight_kg × 0.04 (boys) or × 0.03 (girls)
- Daily calories: (5 × weight_kg + 6.25 × height_cm ± sex_factor) × 1.2 via Mifflin-St Jeor

**API endpoint:** POST /api/bmi-child — accepts JSON {group, gender, row_index, weight_kg, height_cm, age_years, lang} and returns BMI, category label, SD values, weight range, body fat, water, calories, WHO group label.

## Formulas Reference

All ideal weight formulas are applied per-page and shown side-by-side. For a 170 cm person:

**Devine (1974)**
- Women: 45.5 + 2.3 × (height_in − 60) ≈ 61.4 kg
- Men: 50.0 + 2.3 × (height_in − 60) ≈ 65.9 kg

**Robinson (1983)**
- Women: 49.0 + 1.7 × (height_in − 60) ≈ 60.9 kg
- Men: 52.0 + 1.9 × (height_in − 60) ≈ 65.0 kg

**Miller (1983)**
- Women: 53.1 + 1.36 × (height_in − 60) ≈ 64.0 kg
- Men: 56.2 + 1.41 × (height_in − 60) ≈ 67.5 kg

**BMI-22 target (WHO neutral)**
- Both: 22 × (height_m)² — e.g. 170 cm → 22 × 1.70² ≈ 63.6 kg

Height in inches: height_in = height_cm / 2.54. Average of all four formulas is displayed as the recommended target.

**Historic formulas** (shown for context in comparison table):
- Broca (1871): height_cm − 100
- Noorden (1910): height_cm × 0.42
- Lorentz (1929), Hamwi (1964), Breiman, Taton also listed

## WHO BMI Categories

| Category | BMI Range |
|---|---|
| Severe Thinness | < 16 |
| Moderate Thinness | 16–16.9 |
| Mild Thinness | 17–18.4 |
| Normal (Healthy) | 18.5–24.9 |
| Pre-Obese | 25–29.9 |
| Obese Class I | 30–34.9 |
| Obese Class II | 35–39.9 |
| Obese Class III | ≥ 40 |

## Height Ranges Covered

- Women (metric): 140–200 cm
- Men (metric): 150–220 cm
- Women (imperial): 4 ft 10 in – 6 ft 2 in
- Men (imperial): 4 ft 11 in – 7 ft 3 in

Each height has a dedicated URL with full formula breakdown.

## Languages

- English: `/ideal-weight/` (no prefix)
- Spanish: `/es/peso-ideal/`
- Russian: `/ru/ideal-weight/`

## Water Intake Calculator

Daily hydration calculator at `/water-intake/` (`/es/ingesta-de-agua/` in Spanish, `/ru/water-intake/` in Russian).

**Inputs:** Weight (kg or lbs), gender (male/female), activity level (sedentary/light/moderate/active/very_active), hot climate toggle.

**Formula:**
- Base: weight_kg × 35 ml (men) or 31 ml/kg (women)
- Activity: +175 ml per increment (0.5 h steps), max +700 ml at 2 h/day
- Hot climate (+30°C): +500 ml
- Total clamped to 1,200–6,000 ml

**IoM reference values:**
- Men: 3,700 ml/day total (drinks + food); ~3,000 ml from drinks
- Women: 2,700 ml/day total; ~2,200 ml from drinks

**API endpoint:** POST `/api/water-intake`
Request: `{ weight_kg, gender, activity, hot_climate, lang }`
Response: `{ total_ml, total_l, glasses_250, base_ml, activity_ml, climate_ml, iom_ml, iom_drink_ml, schedule }`

`schedule` — 14 hourly slots (07:00–20:00) with suggested ml per slot.

## Mobile App

- [Download BMI Family App](/download/) — Free iOS and Android app for BMI and ideal weight tracking

## Optional

- [Sitemap](/sitemap.xml)
- [Privacy & Cookies Policy](/legal/)