BMI Calculator
Calculate your Body Mass Index in seconds. Enter height and weight in metric (kg/cm) or imperial (lbs/ft·in) units to see your BMI score, weight category, and the healthy weight range for your exact height.
Your Measurements
Your BMI
24.2
Normal
Healthy weight for your height
53.5 – 72.0 kg
| Category | BMI range |
|---|---|
| Underweight | < 18.5 |
| Normal | 18.5 – 24.9 |
| Overweight | 25 – 29.9 |
| Obese | ≥ 30 |
How It Works
BMI (Body Mass Index) is a simple screening tool that estimates body fatness using height and weight. It was developed by Adolphe Quetelet in the 19th century and is widely used in clinical settings because it requires only two easy measurements. The WHO classifies BMI into four categories: Underweight (< 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), and Obese (≥ 30). BMI has important limitations — it does not directly measure body fat percentage, cannot distinguish muscle mass from fat mass, and may overestimate obesity in muscular individuals or underestimate it in those with low muscle mass (such as the elderly). For Indian adults, research suggests that health risks (diabetes, cardiovascular disease) increase at lower BMI thresholds — the Indian Council of Medical Research recommends using 18–22.9 as the 'Normal' range for Indians.
BMI Formula
Metric: BMI = weight(kg) ÷ height(m)². Imperial: BMI = 703 × weight(lbs) ÷ height(in)².
Example: Height 170 cm, Weight 70 kg → BMI = 70 ÷ (1.70)² = 70 ÷ 2.89 = 24.2 (Normal weight). Healthy weight range at 170 cm: 53.5 – 71.9 kg.
BMI Categories (WHO)
- Underweight
- BMI below 18.5 — may indicate malnutrition or other conditions
- Normal weight
- BMI 18.5 – 24.9 — associated with lowest health risk
- Overweight
- BMI 25 – 29.9 — increased risk of metabolic conditions
- Obese
- BMI ≥ 30 — significantly elevated cardiovascular and metabolic risk
- India-specific note
- Asian/Indian adults face higher risks at lower BMI — overweight threshold often cited as ≥ 23
Frequently Asked Questions
What is BMI and what does it measure?
BMI (Body Mass Index) is a numerical value derived from your height and weight. It is calculated as weight in kilograms divided by the square of height in metres. BMI is a screening tool used to categorise body weight — it does not directly measure body fat. A BMI result tells you whether your weight falls in the underweight, normal, overweight, or obese range relative to your height.
What are the BMI categories?
The WHO BMI classifications are: Underweight — BMI below 18.5; Normal weight — 18.5 to 24.9; Overweight — 25 to 29.9; Obese Class I — 30 to 34.9; Obese Class II — 35 to 39.9; Obese Class III (severe) — 40 and above. These thresholds are the same for men and women. Some countries use modified ranges for specific populations.
Is BMI accurate for everyone?
BMI is a useful population-level screening tool but has known limitations for individuals. It cannot distinguish between muscle mass and fat mass — athletes with high muscle mass can be classified as overweight even with low body fat. It also may not reflect fat distribution (visceral vs subcutaneous fat), which matters for health risk. BMI should be interpreted alongside waist circumference, body composition, and clinical history.
What is a healthy BMI for Indians?
The standard WHO thresholds (Normal: 18.5–24.9) were developed on Western populations. Multiple Indian studies show that Indians develop metabolic risk (insulin resistance, diabetes, hypertension) at lower BMI values. The Indian Consensus Group recommends: Underweight < 18; Normal 18–22.9; Overweight 23–24.9; Obese ≥ 25. The Asia-Pacific WHO guidelines use 23 as the overweight cut-off for Asian populations.
How can I lower my BMI?
BMI decreases when you reduce body weight relative to height (height does not change in adults). Sustainable approaches include: (1) a caloric deficit diet — reducing intake by 300–500 kcal/day leads to 0.5–1 kg/week weight loss; (2) strength training to preserve muscle mass while losing fat; (3) aerobic exercise (150 min/week of moderate intensity per WHO guidelines). Rapid weight loss is typically unsustainable and results in muscle loss; gradual loss of 0.5–1 kg/week is evidence-based.
What is the difference between BMI and body fat percentage?
BMI is a proxy calculated from height and weight alone — it does not actually measure fat. Body fat percentage measures the proportion of your total body mass that is adipose (fat) tissue, typically via DEXA scan, hydrostatic weighing, or bioelectrical impedance. Healthy body fat ranges: men 10–20%, women 18–28% (varies by age). Two people with the same BMI can have very different body fat percentages — a muscular person may have 12% body fat while another with the same BMI may have 28%.