Calculate your Body Mass Index and find your healthy weight range.
Enter height and weight to calculate BMI.
Body Mass Index (BMI) is a measure that uses height and weight to estimate body fat. While not perfect, it's a useful screening tool for potential weight-related health risks.
BMI doesn't distinguish between muscle and fat. Athletes may have high BMI due to muscle. It also doesn't account for age, gender, or body composition. Consult a healthcare provider for complete assessment.
BMI may overestimate body fat in athletes with high muscle mass. Other measures like body fat percentage or waist circumference provide better insights.
Generally 18.5–24.9 is considered healthy, but optimal BMI varies by age, ethnicity, and individual health factors.
Body Mass Index (BMI) is a screening number that compares your weight to your height, calculated as weight in kilograms divided by height in metres squared. It was devised in the 1830s by Belgian statistician Adolphe Quetelet to describe populations, not individuals, and that origin explains both its usefulness and its limits. It is a fast, cheap first look at weight status, and it is not a measure of health.
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BMI is approximately 24.5, at the upper end of the healthy weight band
| Category | BMI Range | What It Signals |
|---|---|---|
| Underweight | Below 18.5 | Worth investigating nutrition and underlying causes |
| Healthy weight | 18.5 to 24.9 | Associated with lowest population-level risk |
| Overweight | 25.0 to 29.9 | Screening flag; needs context to interpret |
| Obesity class I | 30.0 to 34.9 | Increased risk in population studies |
| Obesity class II | 35.0 to 39.9 | Higher associated risk |
| Obesity class III | 40.0 and above | Highest associated risk |
BMI uses two numbers, height and weight. Everything else about your body is invisible to it. This matters more than most people realise.
A rugby player and a sedentary person of the same height and weight get an identical BMI despite completely different body composition. This is not a minor edge case: it affects anyone who trains seriously, and it is the reason BMI should never be the only measure used on an individual.
BMI becomes far more useful when read alongside one or two other simple measures.
| Measure | What It Adds | Rough Guide |
|---|---|---|
| Waist circumference | Abdominal fat, closely tied to metabolic risk | Under 94 cm men, 80 cm women |
| Waist-to-height ratio | Adjusts waist for body size | Keep waist under half your height |
| Body fat percentage | Separates fat from lean mass | Varies by age and sex |
| Blood pressure and glucose | Measures health directly rather than by proxy | Assessed clinically |
Keeping your waist measurement under half your height is a simple check that several researchers argue predicts metabolic risk better than BMI alone. Someone 170 cm tall would aim for a waist under 85 cm. It takes one tape measure and no arithmetic.
Given the criticism, it is fair to ask why BMI persists. The answer is practical: it needs only a scale and a tape measure, costs nothing, and works consistently across large populations. For public health surveillance, tracking obesity trends across millions of people, it does its job well.
The problem arises when a population screening tool is applied to one person as though it were a diagnosis. Read your BMI as one data point that tells you whether a closer look might be worthwhile, and nothing more than that.
BMI is a screening tool, not a diagnosis, and this calculator is for general information only. It does not account for muscle mass, body composition, age or ethnicity. Speak to a doctor for an assessment of your individual health.