Health Tool

BMI Calculator

Calculate your Body Mass Index instantly. Get your BMI category, healthy weight range, and personalized health tips.

Weight (kg)

Height (cm)

Age

Gender

-- BMI

--

Underweight
<18.5 Normal
18.5–24.9 Overweight
25–29.9 Obese
≥30

Ideal Weight (kg)

Weight to Goal

BMI Prime

Est. Body Fat %

BMI Classification Table (WHO Standard)

Category	BMI Range	Health Risk	Action
Severe Underweight	< 16.0	Very High	Immediate medical attention
Moderate Underweight	16.0 – 16.9	High	Consult a doctor
Mild Underweight	17.0 – 18.4	Moderate	Increase caloric intake
Normal Weight	18.5 – 24.9	Low (Healthy)	Maintain current lifestyle
Overweight	25.0 – 29.9	Increased	Diet + exercise
Obese Class I	30.0 – 34.9	High	Medical supervision advised
Obese Class II	35.0 – 39.9	Very High	Medical intervention needed
Obese Class III	≥ 40.0	Extremely High	Urgent medical care

📖 What is BMI?

BMI (Body Mass Index) is a numerical value calculated from your height and weight. It was developed by Belgian mathematician Adolphe Quetelet in the 1830s and is now the most widely used screening tool to identify weight categories.

Formula:
BMI = Weight(kg) ÷ Height(m)²

✅ Why BMI Matters

Simple, fast, and free — no lab test needed
Used by doctors, hospitals, and insurance companies worldwide
Helps identify risk for type 2 diabetes, heart disease, and hypertension
Helps track weight changes over time
Used in large population health studies

⚠️ Limitations of BMI

Does not distinguish fat from muscle
Athletes may show high BMI despite low body fat
Elderly may show normal BMI with low muscle mass
Does not account for fat distribution (belly fat vs. hip fat)
Different BMI thresholds may apply for Asian populations

💡 How to Use BMI Calculator

Choose your preferred unit system (Metric or Imperial)
Enter your current weight accurately
Enter your height (in cm, or feet + inches)
Optionally add age and gender for better estimates
Click "Calculate My BMI"
Review your result and the personalized tips

Real-World Examples

See how BMI is calculated for different people:

Riya Sharma

Age 28 · Female · 55 kg · 163 cm

20.7

Normal Weight ✓

55 ÷ (1.63)² = 20.7 — perfectly in the healthy range.

Arjun Mehta

Age 35 · Male · 92 kg · 175 cm

30.0

Obese Class I

92 ÷ (1.75)² = 30.0 — should consult a doctor and start a fitness routine.

Priya Singh

Age 22 · Female · 45 kg · 162 cm

17.1

Mild Underweight

45 ÷ (1.62)² = 17.1 — needs to increase protein and calorie intake.

Vikram Joshi

Age 45 · Male · 82 kg · 178 cm

25.9

Overweight

82 ÷ (1.78)² = 25.9 — slightly over; can return to normal with moderate exercise.

Frequently Asked Questions

Is BMI accurate for everyone?

BMI is a useful screening tool but not a perfect diagnostic measure. It may be less accurate for athletes, elderly people, pregnant women, and certain ethnic groups. Always pair it with a doctor's evaluation.

What is a healthy BMI for Indians?

For South Asians including Indians, some health authorities suggest a slightly lower threshold. A BMI of 18–22.9 is considered ideal, and overweight starts at 23+, as South Asians tend to carry more visceral fat at lower BMIs.

How often should I check my BMI?

Once every 1–3 months is sufficient for most adults. Daily tracking is unnecessary and may cause anxiety. Focus on gradual, consistent changes rather than frequent measurements.

Can children use this BMI calculator?

No. BMI for children (ages 2–19) uses age- and sex-specific growth charts called BMI-for-age percentiles, which are different from adult BMI categories. Consult a pediatrician for children's weight assessment.