Calculate your Body Mass Index with a visual scale, healthy weight range for your height, BMI Prime, Ponderal Index, and body frame adjustments. Supports adults and children.
Your Measurements
ft
in
lbs
cm
kg
yrs
Wrap your middle finger and thumb around your other wrist. If they overlap: small. If they touch: medium. If they don't: large.
Your BMI Results
1518.525304045+
Underweight <18.5
Normal 18.5–25
Overweight 25–30
Obese 30–40
Severely >40
Your BMI
0
Category
—
BMI Prime
0
Ponderal Index
0
⚖️ Healthy Weight Range for Your Height
Min (BMI 18.5)
—
Max (BMI 25)
—
To reach normal range
—
Frame-adjusted ideal
—
⚠️ BMI has limitations. It doesn't account for muscle mass, bone density, body fat distribution, or age. A muscular athlete may have a "overweight" BMI. Use it as one data point, not a complete health picture.
How You Compare
US adult BMI distribution (CDC data):
What Is BMI?
Also searched as: bmi calculator free | body mass index calculator | am i overweight calculator | bmi calculator pounds and inches Optimized for US users with American units and terminology.
Body Mass Index (BMI) is a measure of body size based on height and weight. It's calculated as weight (kg) divided by height (m) squared: BMI = kg/m². Despite being developed in the 1830s, it remains the most widely used screening tool for weight categories. The WHO defines underweight as BMI <18.5, normal as 18.5–24.9, overweight as 25–29.9, and obese as ≥30.
BMI Prime
BMI Prime is the ratio of your BMI to the upper limit of normal BMI (25). A BMI Prime of 1.0 means you're exactly at the top of the normal range. Below 0.74 is underweight; 0.74–1.00 is normal; above 1.00 means overweight or obese. It's easier to interpret than raw BMI for many people.
Limitations of BMI
BMI is a population-level screening tool, not a personal health diagnosis. It doesn't measure body fat percentage, muscle mass, bone density, or where fat is distributed. Highly muscular individuals often fall in the "overweight" range despite having low body fat. Older adults may have a "normal" BMI but high body fat. Asian populations tend to have higher cardiovascular risk at lower BMI thresholds.
Use the BMI Calculator above — enter your values and get instant results. This free online tool calculates bmi calculator for adults without any download or signup required. Results update in real time as you type.
Use the BMI Calculator above — enter your values and get instant results. This free online tool calculates bmi calculator in pounds and inches without any download or signup required. Results update in real time as you type.
The WHO defines 18.5–24.9 as normal/healthy BMI for adults. For Asian populations, some health organizations recommend lower thresholds (23 for overweight, 27.5 for obese) due to greater metabolic risk at lower BMI levels.
No — BMI is significantly less accurate for muscular athletes. Muscle weighs more than fat, so athletes often register as "overweight" despite having very low body fat percentages. For athletic individuals, body fat percentage (via DEXA scan or skinfold measurements) is a much more useful metric.
The Ponderal Index (PI) = weight(kg) / height(m)³. Unlike BMI which uses height squared, PI uses height cubed, making it more appropriate for very tall or very short individuals. A normal PI is roughly 11–14 kg/m³. It's less commonly used than BMI but more accurate at height extremes.