What's Your BMI?
Calculate your Body Mass Index and see where you fall on the WHO scale, plus your healthy weight range.
How to use this in 60 seconds
- Enter weight in kg and height in cm. For imperial units: 1 lb = 0.45 kg, 1 foot = 30.48 cm, 1 inch = 2.54 cm. 5'10" = 178 cm; 170 lbs = 77 kg.
- Read the BMI number and WHO category. BMI = weight (kg) ÷ height (m)². The WHO ranges: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese. The number alone isn't a diagnosis — it's a population-level screening tool.
- Check the healthy weight range for your height. The tool calculates the weight range that corresponds to a BMI between 18.5 and 24.9 for your specific height. This is more actionable than the BMI number itself — you'd need to gain/lose X kg to enter the healthy range.
BMI is a screening tool, not a verdict
BMI was developed by Adolphe Quetelet in the 1830s as a way to describe the "average man" in epidemiological studies — it was never meant for individual diagnosis. The WHO adopted it for population-level public health work because it's easy to measure and correlates well with health outcomes across large groups. For any individual, it has significant blind spots.
A more honest view: BMI is a useful first-pass signal. If your BMI is in the normal range and you have no other risk factors, that's a green light. If it's outside the normal range, treat it as a prompt to look at the supporting metrics — waist circumference (target <94 cm men / <80 cm women), body fat percentage if you have access to a DEXA or InBody scan, resting heart rate, and your blood pressure.
Calculation runs locally. We don't store your inputs. Not medical advice — consult a healthcare professional for personalized health assessment.
Where BMI gets it wrong
- Athletes and muscular builds. Muscle is denser than fat. A 5'10" 200 lb bodybuilder at 10% body fat has a BMI of 28.7 ("overweight") despite being in elite physical condition. Many NFL players have BMIs in the obese range.
- Older adults losing muscle mass. Sarcopenia (age-related muscle loss) means seniors can have a "normal" BMI while having dangerously low muscle and elevated fat percentage. A 70-year-old with BMI 22 may actually have higher health risk than one at BMI 25 with maintained muscle.
- Ethnic variation. The WHO categories were derived from European/North American populations. For East and South Asian populations, health risks rise at lower BMIs — many Asian health authorities use 23+ as overweight and 27+ as obese.
- Distribution matters as much as total. Visceral fat (around organs) drives most of the health risk associated with high BMI. Two people at BMI 28 with different fat distributions — apple shape vs pear shape — have meaningfully different cardiovascular and metabolic risk.