BMI Calculator
Calculate your Body Mass Index, see your WHO category, healthy weight range, and optional BMR.
About this tool
A complete BMI calculator that supports both metric (cm/kg) and imperial (ft, in/lbs) units. Computes your Body Mass Index, classifies it using WHO categories, shows the healthy weight range for your height, and optionally estimates your Basal Metabolic Rate using the Mifflin-St Jeor equation.
How to use it
Quick steps to get the most out of this utility.
- 1
Choose your unit system
Toggle between Metric (cm/kg) and Imperial (ft, in/lbs) at the top.
- 2
Enter your height and weight
Type your measurements — your BMI and category appear instantly.
- 3
Optionally add age for BMR
Expand the BMR section, enter your age and sex to get your daily calorie baseline.
Understanding your BMI
BMI is a widely used screening tool, but it has limitations. It does not distinguish between fat mass and muscle mass, which means athletes may have a high BMI without excess body fat. It also does not account for where fat is distributed in the body — visceral (abdominal) fat is more strongly associated with metabolic risk than subcutaneous fat.
For most adults, BMI provides a useful first approximation. A result in the overweight or obese range is a prompt to investigate further — not a diagnosis. Your healthcare provider can assess additional factors like waist circumference, blood pressure, blood glucose, and cholesterol to give a fuller picture.
Frequently asked questions
What is BMI?+
BMI (Body Mass Index) is a screening metric calculated by dividing weight in kilograms by height in metres squared. It is used to categorise weight status as Underweight (<18.5), Normal (18.5–24.9), Overweight (25–29.9), or Obese (≥30).
How do I calculate BMI in imperial units?+
BMI = (weight in lbs × 703) ÷ (height in inches)². Enter your height in feet and inches and your weight in pounds — the calculator converts automatically.
What is a healthy BMI?+
According to the WHO, a BMI between 18.5 and 24.9 is considered normal weight for most adults. However, BMI does not account for muscle mass, bone density, or body fat distribution.
What is BMR and how is it calculated?+
BMR (Basal Metabolic Rate) is the number of calories your body needs at complete rest. This calculator uses the Mifflin-St Jeor equation: (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5 (male) or −161 (female).
What is the healthy weight range for my height?+
The healthy weight range is the weight corresponding to a BMI of 18.5–24.9 for your specific height. The calculator shows this range in kg or lbs automatically.
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