body mass index · healthy range · waist-to-height ratio · trend over time
Your details
BMI Result
0.0
1518.5253040+
BMI Prime
—
1.0 = upper healthy limit
Waist-to-Height
—
Your BMI history
How it works
Choose your units. Toggle between metric (kg/cm) or imperial (lb/in).
Enter your height and weight. These are the only two numbers BMI needs.
Get your result instantly. Your BMI is calculated as weight ÷ height², then matched to a category (underweight, normal, overweight, obese) and shown on the color-coded scale.
See your healthy range. The result also shows the weight range considered "normal BMI" for your specific height.
BMI is a quick screening number based on height and weight alone — it doesn't account for muscle mass, bone density, or body composition. Use it as a starting point, not a full picture of your health.
BMI categories at a glance
Category
BMI range
General guidance
Underweight
Below 18.5
Worth discussing with a doctor, especially with unintentional weight loss.
Normal weight
18.5–24.9
Associated with lower average health risk in most population studies.
Overweight
25–29.9
Worth monitoring, especially alongside other risk factors like waist size.
Obese
30 and above
Higher associated health risk — consider talking to a doctor about next steps.
Some health organizations, including several in Asia, use lower BMI cutoffs (e.g. 23 for overweight, 27.5 for obese) because health risk tends to appear at a lower BMI in some populations. If you're unsure which reference applies to you, ask your doctor.
Frequently asked questions
For most adults, a BMI between 18.5 and 24.9 is considered the "normal weight" range on the standard BMI chart. Below 18.5 is underweight, 25–29.9 is overweight, and 30+ is obese.
Not perfectly — BMI doesn't distinguish between muscle and fat, so very muscular people can show a higher BMI without excess body fat. It's a useful screening tool, not a full diagnosis.
BMI is your weight divided by your height squared (kg/m²), or weight in pounds divided by height in inches squared, multiplied by 703.
Yes — toggle between metric and imperial units depending on what you're comfortable with.
After you calculate your BMI, the result also shows the specific weight range considered "normal BMI" for your exact height.
Waist-to-height ratio (WHtR) divides your waist measurement by your height. A ratio under 0.5 is generally considered healthy. Some researchers consider it a better indicator of abdominal fat and related health risk than BMI alone, since it accounts for where fat is carried.
The standard BMI categories were developed mainly from studies in European populations. Several health organizations, including ones in parts of Asia, recommend lower cutoffs (around 23 for overweight and 27.5 for obese) since health risks can appear at a lower BMI in some populations.
Yes. For children and teens, BMI is interpreted using age- and sex-specific percentile charts rather than the fixed adult categories, since healthy body composition changes a lot during growth. This calculator is designed for adults; a pediatrician can assess BMI-for-age for children.
Yes. After calculating your BMI, you can save the result. Saved results are stored privately in your browser (not on a server) and shown as a simple trend so you can see how your BMI has changed over time.
BMI is a general screening tool based on height and weight only — it doesn't account for muscle mass, bone density, age, or body composition. It's not a diagnosis. For a full picture of your health, talk to a doctor.