BMI Calculator
BMI (Body Mass Index) is a widely used screening tool that estimates whether your body weight is appropriate for your height. It is calculated by dividing your weight in kilograms by the square of your height in metres — or, in the imperial formula used below, by multiplying the result of weight divided by height squared by 703.
BMI is a useful general indicator for most adults, but it has well-known limitations. It does not directly measure body fat, and it can be misleading for certain groups including children and teenagers, highly muscular individuals such as athletes and bodybuilders, pregnant women, and the elderly, who tend to lose muscle mass with age. For these groups, BMI should be interpreted with extra caution and ideally discussed with a healthcare professional.
Calculate Your BMI
Enter your weight in poundsEnter your height in inches
Your BMI:
BMI Ranges Explained
The standard BMI categories for adults aged 18 and over, as defined by the CDC and WHO, are as follows:
| BMI Range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy Weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
A BMI in the healthy weight range does not guarantee good health, and a BMI outside it does not necessarily indicate poor health. It is one data point among many that doctors and dietitians use when assessing overall wellbeing.
What To Do With Your BMI Result
If your BMI falls in the underweight range, it may be worth speaking to a doctor or dietitian to rule out underlying causes and ensure you are getting adequate nutrition. Underweight individuals can be at increased risk of nutrient deficiencies, bone loss, and immune system issues.
If your BMI is in the overweight or obese range, gradual changes to diet and physical activity are generally the most sustainable path to improvement. Tracking your daily calorie intake is one of the most effective tools for managing weight — research consistently shows that people who monitor what they eat lose more weight and keep it off longer than those who do not.
Our food database contains over 350,000 foods so you can look up exactly what is in the food you eat every day. Use our free Food Tracker and Exercise Tracker to monitor your intake and activity alongside your BMI progress.
Limitations of BMI
BMI was originally developed in the 1830s by Belgian mathematician Adolphe Quetelet as a population-level statistical tool, not as an individual health diagnostic. It has several well-documented limitations worth understanding:
It does not distinguish between fat and muscle. A highly muscular person may have a high BMI despite having very low body fat. This is why many elite athletes register as overweight or even obese by BMI standards despite being in excellent physical condition.
It does not account for fat distribution. Where fat is stored matters significantly for health risk. Visceral fat around the abdomen is associated with higher cardiovascular and metabolic risk than fat stored elsewhere, but BMI does not capture this distinction. Waist circumference is often a more useful complement to BMI for assessing this risk.
It varies in accuracy across ethnicities. Research suggests that health risks associated with excess body fat begin at lower BMI thresholds for some ethnic groups, particularly South Asian populations. Some health guidelines now use adjusted cutoffs for these groups.
Despite these limitations, BMI remains a useful, free, and widely understood screening tool when interpreted in context.
People who track the calories in the food they eat stay healthier and lose more weight than those who do not. The CalorieDetails food database has over 350,000 foods so you can see exactly what is in the food you are eating every day.
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