Calculate your Body Mass Index (BMI) instantly with this free online BMI calculator. Switch between metric and imperial units, and compare your BMI against WHO global categories and the more conservative Asian-Indian categories that the Government of India uses.
Ages 2 to 120
BMI 22.9 kg/m²
Normal weightYour weight is inside the healthy range for your height.
BMI is a screening number, not a diagnosis. It cannot tell muscle from fat, so athletes, older adults and pregnant women should read it together with other measures. For children and teens (2 to 19) the result is a percentile of the CDC growth charts, estimated for the middle of the entered year of age.
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Body Mass Index is the most widely used population-level indicator of body weight in relation to height. Developed by Belgian mathematician Adolphe Quetelet in the 1830s and adopted by WHO as a global standard in the 1990s, it remains the first-pass screening tool used by doctors, life insurers, fitness coaches and public health programmes worldwide. The strength of BMI is its simplicity: two measurements (height and weight) and a single formula produce a number that correlates reasonably well with overall body fatness across the general population.
For Indians specifically, the WHO has acknowledged that the standard global BMI ranges underestimate cardio-metabolic risk in South Asian bodies. We tend to accumulate more visceral fat at the same BMI compared to Caucasian populations, and our risk of type-2 diabetes, hypertension and metabolic syndrome rises at lower BMI thresholds. The Indian Ministry of Health, ICMR and the Asia-Pacific WHO use a stricter classification: BMI ≥ 23 is overweight, BMI ≥ 25 is obese - compared to ≥25 and ≥30 in the global framework. This calculator shows you both classifications so you can see where you stand under each.
Pick your unit system - metric (cm, kg) or imperial (ft/in, lb).
Enter your height and weight.
Optionally choose your gender and age for a more contextual result.
View your BMI, the WHO category, and the Asian-Indian category.
Use the healthy weight range below the result to set a goal weight.
BMI is a quick screening number that compares your weight to your height. It does not measure body fat directly, but for most people it correlates well with overall body fatness. The same BMI can mean different things across body types - athletes with high muscle mass may register as overweight without being unhealthy.
BMI = weight (kg) / [height (m)]²
The BMI formula divides body weight in kilograms by the square of height in metres. For imperial inputs (pounds, inches), the formula multiplies by 703 to keep the same numeric scale. The result lands in one of four standard categories under the WHO global framework: Underweight (under 18.5), Normal (18.5-24.9), Overweight (25-29.9), Obese (30+). The Asian-Indian framework shifts these down by 2 units: Overweight at 23+, Obese at 25+ - reflecting the increased disease risk South Asian populations carry at lower body weights.
BMI is not a measure of body composition. It can't distinguish between muscle, fat, bone or water - it's simply a weight-for-height ratio. A 1.75m tall, 80kg muscular athlete has the same BMI (26.1) as a 1.75m tall, 80kg sedentary office worker, even though their body compositions are wildly different. For most non-athletic adults aged 20-65, BMI correlates well with body fat percentage. For competitive athletes, bodybuilders, the elderly (with sarcopenia), and pregnant women, BMI is unreliable - use body fat percentage, waist circumference, or DEXA scan instead.
Beyond BMI, two related measurements add critical context: waist circumference and waist-to-hip ratio. WHO recommends waist circumference under 90cm for men and 80cm for women in South Asia. The Indian Diabetes Federation considers waist over 90cm (men) or 80cm (women) as a key metabolic syndrome criterion. Even normal-BMI individuals with high waist circumference carry elevated cardio-metabolic risk - the so-called 'skinny fat' phenotype common among urban Indians.
Height 1.73m. BMI = 75 / (1.73)² ≈ 25.1. WHO category: Overweight (just above 25). Asian-Indian category: Obese (above 25). The same individual at 70 kg would be 23.4 BMI - overweight by Indian standards, normal by global. The 5 kg difference between health categories is a typical 'workable' weight-loss goal.
Height 1.63m. BMI = 58 / (1.63)² ≈ 21.8. WHO category: Normal. Asian-Indian category: Normal. Good zone. If waist circumference is also under 80cm, this individual is at low metabolic risk despite the higher visceral fat tendency in Indian females.
These are the World Health Organization (WHO) cut-offs for adults aged 20 and over. They apply to men and women alike and are the most widely used reference around the world.
| Classification | BMI (kg/m²) | BMI Prime |
|---|---|---|
| Severe Thinness | < 16 | < 0.64 |
| Moderate Thinness | 16 – 17 | 0.64 – 0.68 |
| Mild Thinness | 17 – 18.5 | 0.68 – 0.74 |
| Normal | 18.5 – 25 | 0.74 – 1.00 |
| Overweight | 25 – 30 | 1.00 – 1.20 |
| Obese Class I | 30 – 35 | 1.20 – 1.40 |
| Obese Class II | 35 – 40 | 1.40 – 1.60 |
| Obese Class III | ≥ 40 | ≥ 1.60 |
People of South and East Asian descent tend to carry more body fat, and more of it around the abdomen, at the same BMI. WHO and Indian guidelines therefore flag risk earlier, from a BMI of 23.
| Classification | BMI (kg/m²) |
|---|---|
| Underweight | < 18.5 |
| Normal | 18.5 – 23 |
| Overweight (at risk) | 23 – 25 |
| Obese Class I | 25 – 30 |
| Obese Class II | ≥ 30 |
Find your height on the vertical axis and your weight along the bottom. The colour where they meet is your category.
Adult cut-offs do not apply while a child is growing. The US Centers for Disease Control and Prevention (CDC) compare a child’s BMI with other children of the same age and sex and report a percentile. The calculator above does this for you using the CDC growth chart data.
| Category | Percentile range |
|---|---|
| Underweight | < 5% |
| Healthy weight | 5% to 85% |
| At risk of overweight | 85% to 95% |
| Overweight | ≥ 95% |
Worked example for a person who is 5 ft 10 in (1.778 m) tall and weighs 160 lb (72.57 kg):
Metric (SI)
BMI = mass (kg) ÷ height² (m²)
= 72.57 ÷ 1.778² = 23.0
US customary
BMI = 703 × mass (lb) ÷ height² (in²)
= 703 × 160 ÷ 70² = 23.0
BMI Prime is your BMI divided by 25, the top of the normal range. A value below 0.74 is underweight, 0.74 to 1 is normal, and above 1 is overweight. Because it has no unit, it is easy to compare against the different upper limits that some countries use.
The Ponderal Index divides mass by height cubed (kg/m³) instead of squared. It behaves better than BMI for very tall and very short people. For the example above: 72.57 ÷ 1.778³ = 12.9 kg/m³.
BMI measures weight relative to height, not body fat. It misses where fat is stored and cannot separate muscle from fat. Keep these in mind when you read your result:
For most adults BMI still tracks body fat reasonably well, so use it as a first check and pair it with waist size, blood pressure and blood tests.
The WHO defines a healthy BMI as 18.5 to 24.9. For Indian and other South Asian populations, doctors often use a stricter range of 18.5 to 22.9 because of higher cardio-metabolic risk at the same BMI.
Indian and South Asian populations tend to have higher body fat and visceral fat at the same BMI compared to Caucasian populations. Indian medical bodies and the WHO Asia-Pacific guidelines use a lower overweight cutoff (BMI ≥ 23) and obesity cutoff (BMI ≥ 25).
Not always. BMI does not distinguish between fat and muscle, so muscular individuals may show high BMI without being unhealthy. Pair BMI with waist measurement or body fat % for a clearer picture.
No. Children's BMI is interpreted using age-specific growth charts. BMI also doesn't apply during pregnancy. Use a doctor-recommended method instead.
Slow, steady progress works best - a 10–15% reduction in body weight over 6–12 months through a moderate calorie deficit and regular activity is sustainable and improves most cardio-metabolic markers.
No. BMI is a starting point, not a diagnosis. Consider waist-to-hip ratio, body fat %, blood pressure, blood sugar, lipid profile, and family history. A doctor can interpret the full picture.
Body composition, daily energy needs and pregnancy timelines all rest on formulas validated across millions of people, but no single number tells the whole story. The values from this calculator are point estimates with a known margin of error - body fat from skinfold or US Navy method has roughly a ±3% standard error compared to a DEXA scan, and BMR can vary ±10% person to person at the same height and weight. Use these numbers to track trends week over week, not to chase decimal precision day to day.
Pair this tool with the BMR, TDEE, calorie and macro calculators to turn a single measurement into an actionable plan. None of these tools are a substitute for a qualified doctor, registered dietitian or certified strength coach - but they remove the busywork so you spend more time on training and recovery, less on math.
The BMI Calculator is part of the Health & Fitness suite on Online Calculator Tools, alongside 6 related calculators. All tools share the same UI patterns, the same privacy-first rendering (nothing is sent to a server), and the same commitment to showing the formula and assumptions behind every result.
