Calculate adult BMI from height and weight and place the result on a clear reference scale.
Enter your measurements. Imperial units are selected by default.
A mathematical reference for your height, not a personalised weight target.
BMI Prime compares your BMI with 25 (below 1: under the overweight threshold). The ponderal index, weight ÷ height³, stays steadier for very tall or very short people.
Add the waist-to-hip ratioBMI does not show where fat sits: the waist-to-hip ratio spots abdominal fat, more closely linked with cardiovascular risk.BMI is calculated from weight and height. The displayed categories use the World Health Organization adult BMI reference ranges.
BMI = weight (kg) ÷ height² (m)BMI is calculated from weight and height. The displayed categories use the World Health Organization adult BMI reference ranges.
BMI = 703 × weight (lb) ÷ height² (in)BMI is a simple indicator that relates weight to height. This calculator gives your value, places it within adult reference ranges, and explains what that number can - and cannot - tell you about body size.
Enter your height and weight in metric, imperial or stones: the result appears as you type. The tool converts units when needed and returns the same body mass index.
The result is shown on a gauge so you can immediately see its position relative to the main adult thresholds. The calculator also displays the weight range that mathematically corresponds to BMI 18.5-24.9 for the entered height.
BMI is useful as a standardised screening indicator, but it cannot by itself describe body composition or a person's overall health.
Use centimetres or feet and inches.
Use kilograms or pounds.
See your BMI on the gauge, its adult reference category and the mathematical reference-weight range.
The gauge places BMI within four broad adult references: underweight, normal weight, overweight and obesity. These categories help interpret a number, but they do not establish a diagnosis or summarise a person's health.
BMI uses total body weight and cannot distinguish muscle, fat, bone or body water. Two adults with the same BMI can therefore have very different body compositions.
Substantial muscle mass can raise BMI without reflecting body fat in the same way. Individual context and other indicators may be needed when assessing health.
Children and teenagers require age- and sex-specific growth references. Pregnancy also changes how weight should be interpreted, so this calculator is not intended for those situations.
The calculation is deliberately simple, but interpreting it requires context. These are the key points behind the result shown by the calculator.
BMI = weight (kg) ÷ height² (m)
For 70 kg and 1.75 m: 70 ÷ (1.75 × 1.75) ≈ 22.9. With pounds and inches, the equivalent formula uses the factor 703.
Changing units changes how the formula is written, not the final BMI value.
The thresholds place adult BMI into broad weight-status categories.
BMI is a screening indicator based only on height and weight. Individual assessment can require other information.
Muscle contributes to body weight. A very muscular person can therefore have a high BMI even when the number does not accurately describe body composition.
The calculator applies BMI limits 18.5 and 24.9 to the entered height. The resulting range is purely mathematical.
Get BMI from height and weight and see where it sits within standard adult reference ranges.
See the 18.5, 25 and 30 thresholds and what the corresponding category means.
Learn why BMI needs context, particularly when muscle mass or other individual factors affect body weight.
BMI is weight in kilograms divided by height in metres squared. For example, 70 kg at 1.75 m gives a BMI of about 22.9.
For adults, BMI below 18.5 is underweight, 18.5 to 24.9 is healthy weight, 25 to 29.9 is overweight, and 30 or above is obesity. Obesity can be further divided into classes.
No. The adult formula uses height and weight, and standard adult categories are not changed by sex. Children and teenagers require age- and sex-specific interpretation.
Yes. BMI cannot distinguish fat from muscle and bone, so a person with substantial muscle mass can have a high BMI that does not precisely describe body composition.
This calculator is not designed to interpret pregnancy-related weight changes. Pregnancy requires different context and appropriate professional guidance.
No. BMI in children and teenagers is interpreted using age- and sex-specific growth references or percentiles. This calculator uses adult reference ranges.
No. It only shows the weights that mathematically produce a BMI from 18.5 to 24.9 for the entered height. It is not a personalised target or medical recommendation.
No. BMI is one indicator. Medical history, body composition, blood pressure, laboratory findings and other factors may matter in an individual health assessment.
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