BMI Calculator

by QuickToolkit

Height (cm)

Height

Weight (kg)

Please enter valid height and weight.

Your BMI

0.0

Body Mass Index

UnderweightNormalOverweightObese

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Height

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Weight

Underweight

BMI < 18.5

Normal

18.5 – 24.9

Overweight

25.0 – 29.9

Obese

BMI ≥ 30

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What is BMI?

BMI, or Body Mass Index, is a widely used screening tool to estimate whether a person has a healthy body weight relative to their height. It is calculated by dividing your weight in kilograms by the square of your height in meters (kg/m²). While BMI does not directly measure body fat, it is a reliable and quick indicator used by doctors and health professionals worldwide to identify potential weight-related health risks.

The World Health Organisation (WHO) classifies BMI into four main categories: Underweight (below 18.5), Normal weight (18.5–24.9), Overweight (25.0–29.9), and Obese (30 and above). For South Asian populations, including Indians, research suggests that health risks may begin at lower BMI values, with some experts recommending an adjusted cutoff of 23 for overweight and 27.5 for obesity.

How to Use This BMI Calculator

Enter your height (in centimetres or feet and inches) and your weight in kilograms. Click "Calculate BMI" and the result will show your BMI score, the health category it falls into, and a visual scale so you can see where you stand. The calculator also displays your height and weight for easy reference.

This tool is intended for adults aged 18 and above. It is not suitable for pregnant women, athletes, bodybuilders, or children, as BMI interpretation differs for these groups. Always consult a qualified healthcare provider for personalised medical advice.

Who Uses a BMI Calculator?

Body Mass Index is a screening metric used worldwide because it's simple, cheap, and correlates reasonably well with body-fat levels in most adults. Typical users include:

Fitness beginners: Tracking BMI alongside weight is a practical way to know whether a weight-loss or muscle-gain plan is moving you in the right direction.

Routine health check-ups: Doctors note BMI on every physical; calculating it at home helps you arrive informed and discuss trends over time.

Insurance & medical forms: Life-insurance underwriters, pre-employment medicals, and gym memberships all record BMI as a baseline measure.

Diet & nutrition planning: Dieticians use BMI as a starting point for recommending calorie targets, though they will always combine it with waist circumference and activity level.

Example

A person who is 170 cm tall and weighs 72 kg has a BMI of 72 ÷ (1.70 × 1.70) = 24.9, placing them at the upper edge of the “Normal” range (18.5–24.9). Gaining just 1 kg would push them into the “Overweight” band, which is useful context when setting maintenance goals. Remember: BMI is a screening tool, not a diagnosis. Athletes with high muscle mass and older adults with reduced muscle may score outside the “Normal” range despite being healthy — always combine BMI with waist-to-hip ratio, body-fat percentage, and medical advice.

Frequently Asked Questions

While the global WHO standard defines healthy BMI as 18.5–24.9, many Indian and Asian health guidelines suggest a lower threshold. A BMI of 18.5–22.9 is often considered ideal for South Asians, with overweight starting at 23 and obesity at 27.5, due to higher body fat percentage at lower BMI levels compared to Caucasians.

BMI is a useful screening tool but it has limitations. It does not account for muscle mass, bone density, fat distribution, age, or sex. Athletes and bodybuilders may have a high BMI due to muscle rather than fat. For a more complete picture, consider additional measurements like waist circumference, body fat percentage, or blood tests.

To move into a healthier BMI range, focus on a balanced diet rich in whole grains, vegetables, lean protein, and healthy fats, combined with regular physical activity (at least 150 minutes of moderate exercise per week). Avoid crash diets and seek guidance from a certified nutritionist or doctor for safe and sustainable weight management.