BMI Calculator – Check Your Body Mass Index Instantly
Use this free BMI calculator to find out your Body Mass Index based on your height and weight. Instantly know whether you fall in the underweight, healthy, overweight or obese range — with no signup needed. Works on mobile and desktop.
What is BMI?
Body Mass Index (BMI) is a numerical value calculated from a person's weight and height. It provides a simple, widely-used indicator of whether a person has a healthy body weight relative to their height. BMI is used by doctors, nutritionists and health organisations worldwide as a quick screening tool for weight-related health risks.
BMI Formula
BMI = Weight (kg) ÷ Height² (m²)
Example: Weight = 70 kg, Height = 1.75 m → BMI = 70 ÷ (1.75 × 1.75) = 22.9
BMI Categories (WHO Standard)
| BMI Range | Category | Health Risk |
|---|
| Below 18.5 | Underweight | Risk of malnutrition, anaemia, osteoporosis |
| 18.5 – 24.9 | Normal / Healthy | Low risk — maintain current lifestyle |
| 25.0 – 29.9 | Overweight | Moderate risk of heart disease, diabetes |
| 30.0 – 34.9 | Obese (Class I) | High risk — lifestyle changes recommended |
| 35.0 – 39.9 | Obese (Class II) | Very high risk — medical intervention advised |
| 40.0 and above | Obese (Class III) | Extremely high risk — urgent medical attention |
BMI for Indian Adults
The WHO BMI thresholds above are designed for Western populations. Research shows that Indians and other South Asians have a higher risk of metabolic diseases at lower BMI values. The Indian Council of Medical Research (ICMR) recommends using modified cut-offs for Indian adults:
| BMI Range | Category (Indian Adults) |
|---|
| Below 18.0 | Underweight |
| 18.0 – 22.9 | Normal Weight |
| 23.0 – 24.9 | Overweight |
| 25.0 and above | Obese |
⚠️ BMI is a screening tool, not a diagnosis. It does not account for muscle mass, bone density, body fat distribution or age. Consult a doctor for a complete health assessment.
Frequently Asked Questions
Is BMI accurate for athletes?No. Muscle is denser than fat, so athletes with high muscle mass often have a high BMI despite having low body fat. BMI can misclassify fit, muscular individuals as overweight or obese.
What is a healthy BMI for women vs men?The BMI scale itself does not differ by gender. However, women naturally carry more body fat than men at the same BMI. A BMI of 22 is considered equally healthy for both sexes under standard guidelines.
How do I reduce my BMI?BMI decreases when you lose body fat. The most effective approach combines a calorie-controlled diet, regular aerobic exercise (150+ minutes/week) and strength training. Consult a nutritionist for a personalised plan.
Can children use this BMI calculator?No. Adult BMI categories do not apply to children. For children aged 2–18, BMI is calculated the same way but assessed against age- and sex-specific percentile charts (CDC or WHO growth charts).
What is the BMI of a 70 kg person who is 5'7" tall?5'7" = 1.70 m. BMI = 70 ÷ (1.70 × 1.70) = 70 ÷ 2.89 ≈ 24.2 — which falls in the Normal/Healthy range.