Calculate your Body Mass Index using metric or imperial units. See your BMI category, healthy weight range, and waist-to-height ratio for a more complete picture of health risk.
Waist-to-height ratio predicts cardiometabolic risk better than BMI.
General health information, not medical advice. Discuss your numbers with a qualified clinician.
Body Mass Index compares your weight to your height. It is the most widely used health screening number in the world, and also one of the most widely misinterpreted. This calculator gives you your BMI, your healthy weight range, and - more usefully - your waist-to-height ratio.
Where
Muscle versus fat. BMI measures total mass. Two people at the same height and weight can have completely different body composition and identical BMI.
Fat distribution. This is the bigger failure. Visceral fat packed around the liver and pancreas drives insulin resistance and cardiovascular risk. Subcutaneous fat on hips and thighs is comparatively benign. BMI cannot tell them apart; waist circumference can.
Height scaling. Dividing by height squared is a mathematical convenience, not biology. It systematically over-reports for tall people and under-reports for short people.
Population differences. Risk emerges at lower BMI values in Asian populations, which is why the WHO recommends lowered action points of 23 and 27.5.
Choose your units
Switch between imperial (feet, inches, pounds) and metric (centimetres, kilograms). Conversions are handled automatically.
Enter height and weight
Use the sliders for quick adjustment or type exact values. Your BMI updates live along with the category gauge.
Add your waist measurement
Measure at the navel, standing relaxed, exhaling normally. This produces a waist-to-height ratio, which is the more informative number.
Interpret in context
Check whether you are within the healthy weight range for your height, and whether your waist is under half your height.
General health screening
A quick first check on whether weight is worth discussing with a clinician.
Tracking progress
With height constant, BMI change tracks weight change over months - useful as a trend, not a daily metric.
Setting a target weight
See the exact weight range that corresponds to a normal BMI for your height.
Insurance and clinical thresholds
Some programmes, medication dosages and surgical eligibility criteria reference BMI, so the number has practical consequences.
The WHO defines 18.5 to 24.9 as normal weight, 25 to 29.9 as overweight, and 30 or above as obese. For South Asian, Chinese and other Asian populations, lower action points of 23 and 27.5 are recommended because cardiometabolic risk appears at lower BMI values.
No. BMI measures mass relative to height and cannot distinguish muscle from fat. Muscle is denser than fat, so a lean, muscular person is frequently classified as overweight or obese. A 6'0" athlete at 220 lb and 10% body fat has a BMI of 29.8 despite excellent health.
The formula and thresholds are identical. Women typically carry a higher healthy body-fat percentage than men at the same BMI, which is one more reason the number is a rough screen rather than a measure of body composition.
Divide your waist circumference by your height in the same units. Keeping it under 0.5 - waist less than half your height - is a simple rule that predicts cardiometabolic risk better than BMI, because it captures visceral fat around the organs, which is the metabolically dangerous kind.
A deficit of roughly 500 calories per day produces about 1 lb of loss per week, which is a sustainable rate. Combine it with resistance training to preserve muscle, since losing muscle lowers BMI without improving health. Rapid loss above 2 lb per week tends to sacrifice lean mass.