BMI Calculator: Check Your Body Mass Index

Q: How is BMI calculated?

BMI is calculated by dividing your weight in kilograms by your height in meters squared. The formula is BMI = weight (kg) / height (m)^2. For example, a person weighing 70 kg and standing 1.75 m tall would have a BMI of 22.9.

Q: What is a healthy BMI range for Indians?

By WHO global standards, healthy BMI is 18.5 to 24.9. For Indians and people of South Asian descent, the ICMR and India's Ministry of Health recommend a lower upper limit: 18.5 to 22.9 is Normal, 23 to 27.4 is Overweight, and 27.5 and above is Obese. This is because South Asians accumulate more abdominal fat at the same BMI, leading to higher metabolic risk at lower BMI values.

Q: Is BMI accurate for athletes?

BMI may not be accurate for athletes or highly muscular individuals because it does not distinguish between muscle mass and fat mass. A muscular person may have a high BMI despite having low body fat, so additional measurements like body fat percentage are recommended.

Q: What are the BMI categories for Indians vs globally?

WHO global: Underweight (below 18.5), Normal (18.5–24.9), Overweight (25–29.9), Obese (30 and above). Indian/Asian thresholds (WHO 2004, ICMR): Normal (18.5–22.9), Overweight (23–27.4), Obese (27.5 and above). The key difference is in the 23–24.9 range: globally Normal, but Overweight by Indian clinical guidelines.

Q: Can BMI be used for children?

For children and teens aged 2 to 19, BMI is calculated the same way but interpreted using age- and sex-specific percentiles rather than fixed categories. A pediatric BMI percentile chart is used because body composition changes as children grow.

Q: Does BMI differ by gender?

The BMI formula itself is the same for both genders, but women naturally tend to carry more body fat than men at the same BMI value. Some health professionals suggest using gender-specific thresholds for a more accurate health assessment.

Q: What are the limitations of BMI?

BMI does not account for muscle mass, bone density, age, gender, or fat distribution. It is a screening tool, not a diagnostic measure. People with the same BMI can have very different health profiles, so it should be used alongside other assessments.

Q: What waist size indicates health risk for Indians?

WHO Asia-Pacific guidelines recommend: men above 90 cm (35.4 inches) and women above 80 cm (31.5 inches) indicate elevated metabolic risk. These are lower than Western thresholds (men: 102 cm, women: 88 cm). A waist above these thresholds signals elevated risk even if BMI is in the Normal range.

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Height (cm)

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About This Calculator

What it calculates: Body Mass Index (BMI) and corresponding WHO weight category.
Inputs required: Height (cm or ft/in), weight (kg or lbs)
Outputs: BMI value, weight category (Underweight / Normal / Overweight / Obese)
Formula: BMI = Weight (kg) / Height (m)^2
Assumptions: WHO global adult categories: <18.5 Underweight, 18.5–24.9 Normal, 25–29.9 Overweight, ≥30 Obese. Asian/Indian thresholds (WHO 2004, India MoHFW): Overweight ≥23, Obese ≥27.5. Not suitable for children or pregnant women.
Last updated: April 2026

How This BMI Calculator Works

BMI (Body Mass Index) is a widely used screening tool that estimates body fat based on two simple measurements: your weight and your height. Developed by Belgian mathematician Adolphe Quetelet in the 19th century, it remains one of the quickest ways to assess whether your weight falls within a healthy range.

To use this calculator, enter your weight in kilograms and your height in centimetres. The tool instantly computes your BMI score and classifies you into one of the standard weight categories: Underweight, Normal weight, Overweight, or Obese. The calculation runs entirely in your browser — no data is stored or sent to any server.

While BMI does not measure body fat directly, it provides a useful starting point for understanding your weight status and identifying potential health risks associated with being underweight or overweight.

BMI Formula

The Body Mass Index formula divides your weight in kilograms by the square of your height in metres:

BMI = Weight (kg) / (Height (m))²

Where weight is measured in kilograms and height is measured in metres. If you enter your height in centimetres (as this calculator accepts), the value is divided by 100 to convert it to metres before applying the formula.

Quick example: A person weighing 70 kg with a height of 175 cm (1.75 m) would have a BMI of 70 / (1.75 × 1.75) = 70 / 3.0625 = 22.9, which falls in the Normal weight category.

Example Calculation

Inputs:

Weight: 68 kg
Height: 170 cm (1.70 m)

Step-by-step:

Convert height to metres: 170 cm / 100 = 1.70 m
Square the height: 1.70 × 1.70 = 2.89
Divide weight by height squared: 68 / 2.89 = 23.5

Result: A BMI of 23.5 falls within the Normal weight category (18.5 to 24.9). This indicates a healthy weight relative to height according to the WHO standard classification.

BMI Categories (WHO Standard)

The World Health Organization (WHO) defines the following BMI categories for adults aged 20 and above. These thresholds are used globally as a standard reference for weight classification:

Underweight: BMI below 18.5 — May indicate nutritional deficiency, eating disorders, or other health concerns. Associated with weakened immunity and bone density loss.
Normal weight: BMI 18.5 to 24.9 — Generally associated with the lowest health risks. Maintaining a BMI within this range is recommended for long-term well-being.
Overweight: BMI 25.0 to 29.9 — Indicates excess body weight that may increase risk of cardiovascular disease, type 2 diabetes, and joint problems.
Obese Class I: BMI 30.0 to 34.9 — Moderate obesity associated with significantly elevated health risks including hypertension and metabolic syndrome.
Obese Class II: BMI 35.0 to 39.9 — Severe obesity with high risk of obesity-related complications and reduced quality of life.
Obese Class III: BMI 40.0 and above — Very severe (morbid) obesity with the highest risk of serious health conditions including heart disease, stroke, and certain cancers.

Note for Asian populations: The WHO suggests lower BMI thresholds for people of Asian descent due to higher health risks observed at lower BMI values. For Asian populations, overweight is defined as BMI 23 or above, and obese as BMI 25 or above. This is because Asian individuals tend to accumulate more visceral fat at lower body weights compared to Caucasian populations.

Limitations of BMI

While BMI is a convenient and widely used metric, it has several important limitations that you should be aware of:

Does not distinguish muscle from fat: Athletes and individuals with high muscle mass may be classified as "overweight" or "obese" despite having low body fat percentages. Muscle weighs more than fat per unit volume, which inflates the BMI score.
Ignores fat distribution: BMI does not account for where fat is stored in the body. Abdominal (visceral) fat carries significantly higher health risks than fat stored in the hips and thighs. Waist circumference and waist-to-hip ratio are better indicators of fat distribution.
Not suitable for all populations: BMI categories may not apply accurately to children, adolescents, elderly individuals, or pregnant women. Age-related muscle loss in older adults can mask high body fat behind a "normal" BMI score.

For these reasons, BMI is best used as an initial screening tool rather than a standalone diagnostic measure. Complement it with waist-to-hip ratio, body fat percentage measurements, blood pressure, and blood lipid panels for a more comprehensive health assessment.

Why Indians Are Overweight at BMI 23, Not 25

The standard WHO BMI chart was developed primarily using data from European and North American populations. A WHO Expert Consultation on Obesity in Asia (published 2004) found that people of South and East Asian descent develop obesity-related health complications at lower BMI values. At the same BMI, South Asians tend to carry significantly more visceral (abdominal) fat than Europeans — the type of fat most strongly associated with type 2 diabetes, hypertension, and cardiovascular disease.

India's Ministry of Health and Family Welfare and the Indian Council of Medical Research (ICMR) have adopted lower cut-offs accordingly. The table below shows the difference:

BMI classification comparison: WHO global vs Indian/Asian thresholds
BMI Range	WHO Global	Indian/Asian (WHO 2004 / ICMR)
Below 18.5	Underweight	Underweight
18.5 – 22.9	Normal weight	Normal weight
23.0 – 24.9	Normal weight	Overweight (elevated risk)
25.0 – 27.4	Overweight	Overweight (high risk)
27.5 – 29.9	Overweight	Obese
30 and above	Obese	Obese

In practice: a 35-year-old Indian at 170 cm and 68 kg has a BMI of 23.5. The WHO global chart calls this Normal weight. Indian clinical guidelines call it Overweight. This person should be monitoring waist circumference, fasting glucose, and blood pressure — steps that the global "Normal" classification might encourage them to skip.

This does not mean you should panic at a BMI of 23. It means the Indian standard prompts earlier lifestyle attention, not clinical intervention. A BMI of 23-24.9 in an Indian adult warrants watching diet, managing stress, and tracking waist circumference — not drastic weight loss. For detailed calorie guidance based on your activity level, see the Calorie Calculator.

Frequently Asked Questions

How is BMI calculated?

BMI is calculated by dividing your weight in kilograms by your height in meters squared. The formula is BMI = weight (kg) / height (m)². For example, a person weighing 70 kg and standing 1.75 m tall would have a BMI of 70 / (1.75 × 1.75) = 22.9.

What is a healthy BMI range for Indians?

By WHO global standards, healthy BMI is 18.5 to 24.9. For Indians and people of South Asian descent, the ICMR and India's Ministry of Health recommend a lower upper limit: 18.5 to 22.9 is Normal, 23 to 27.4 is Overweight, and 27.5 and above is Obese. This is because South Asians accumulate more abdominal fat at the same BMI compared to Europeans, leading to higher metabolic risk at lower BMI values.

Is BMI accurate for athletes?

BMI is not accurate for athletes or highly muscular individuals because it does not distinguish between muscle mass and fat mass. A 90 kg person with 12% body fat may have a BMI of 27 and be classified as Overweight despite excellent metabolic health. For athletes, body fat percentage measured via DEXA scan or skinfold calipers is a better measure.

What are the BMI categories for Indians vs globally?

WHO global: Underweight (<18.5), Normal (18.5–24.9), Overweight (25–29.9), Obese (≥30). Indian/Asian thresholds (WHO 2004 Expert Consultation, ICMR): Underweight (<18.5), Normal (18.5–22.9), Overweight (23–27.4), Obese (≥27.5). The key difference is in the 23–24.9 range, where the global standard calls it Normal but Indian guidelines call it Overweight with elevated health risk.

Can BMI be used for children?

For children and teens aged 2 to 19, BMI is calculated the same way but interpreted using age- and sex-specific percentiles rather than fixed categories. A pediatric BMI percentile chart is used because body composition changes as children grow. This calculator is designed for adults; use a pediatric BMI chart for children.

Does BMI differ by gender?

The BMI formula is the same for both genders, but women naturally carry more body fat than men at the same BMI. A woman with BMI 24 and a man with BMI 24 are both "Normal" by BMI, but the woman likely has a higher body fat percentage. Some health professionals apply gender-specific thresholds, though the Indian/Asian cut-offs (23 for overweight) currently apply to both genders.

What are the limitations of BMI?

BMI does not account for muscle mass, bone density, age, gender, or fat distribution. It cannot tell whether excess weight is fat or muscle, or whether fat is stored harmlessly in the hips or dangerously around organs. It also uses population-level thresholds that were largely derived from Western data. Always use BMI alongside waist circumference, blood pressure, and fasting blood glucose for a meaningful health picture.

What waist size indicates health risk for Indians?

WHO Asia-Pacific guidelines recommend these waist circumference thresholds for Indians: men above 90 cm (35.4 inches) and women above 80 cm (31.5 inches) indicate elevated metabolic risk. These are lower than the Western thresholds (men: 102 cm, women: 88 cm). Measure at the level of your navel while standing and relaxed after exhaling. A waist above these thresholds is a risk signal even if your BMI is in the Normal range.

What BMI Doesn't Show: The Waist Circumference Test

BMI tells you nothing about where fat is stored. Two people at the same BMI — one with a flat stomach and heavy legs, the other with a large waist — have very different metabolic risk profiles. Abdominal fat (visceral fat, stored around organs) raises insulin resistance, blood pressure, and LDL cholesterol. Fat stored in the hips and thighs is largely inert metabolically.

For Indian adults, the WHO Asia-Pacific guidelines recommend these waist circumference thresholds as indicators of elevated metabolic risk:

Men: Waist above 90 cm (35.4 inches) — elevated risk
Women: Waist above 80 cm (31.5 inches) — elevated risk

These are lower than the thresholds used in Western populations (men: 102 cm, women: 88 cm), consistent with the same reasoning behind the lower BMI cut-offs for Asians.

A BMI of 24 with a waist of 92 cm carries more metabolic risk than a BMI of 27 with a waist of 82 cm. The person with the lower BMI is paradoxically at higher risk for diabetes and cardiovascular disease by this measure.

The practical takeaway: if your BMI falls in the 22-27 range and you are Indian, also measure your waist. Take it at the level of your navel while standing relaxed after exhaling. If it is above the thresholds above, that is a more actionable signal than your BMI category alone. For a body fat percentage estimate that goes further than BMI, see the Body Fat Calculator.

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Results are for informational purposes only and do not constitute medical advice. Consult a qualified healthcare professional for personal guidance.

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