The free BMI calculator on this page computes everything the home page calculator does, but lives at its own URL so it can be linked, shared and indexed independently. The result panel includes your BMI value, the WHO category (underweight, normal, overweight, obese) with a colour-coded gauge, BMI Prime (BMI / 25), Ponderal Index, body-fat percentage (Deurenberg, suppressed under 18), healthy weight range, ideal weight (Devine), lean body mass (Boer), BMR (Mifflin–St Jeor) and TDEE at five activity levels. Open the optional waist input for a waist-to-height ratio with a risk label.
What is BMI?
Body Mass Index is a screening number that expresses weight
relative to height. The metric formula is
BMI = weight (kg) / height (m)²; the imperial form
is BMI = 703 × weight (lb) / height (in)². Both give
the same number. The World Health Organization defines a healthy
BMI as 18.5–24.9, overweight as 25.0–29.9, and obese as 30 and
above. For children age 2–19, BMI is interpreted as a CDC
percentile — switch to Child / Teen mode in the
calculator to label against CDC reference bands.
How to use the calculator
- Pick your units — metric, imperial, kg + ft/in, or lb + in.
- Pick the age group — Adult (20+) or Child / Teen (2–19).
- Type your age, gender, height and weight.
- Read your BMI and the follow-on panels (body fat, healthy weight, ideal weight, BMR, TDEE, etc.).
- Optionally save the result, share it via a URL, or download a CSV / PDF.
When the result is misleading
BMI uses only height and weight, so it cannot tell muscle from fat, bone from water, or how weight is distributed. Heavily muscled athletes can read as "overweight" without excess fat, and older adults with sarcopenia can read as "healthy" while having low muscle mass. For a richer picture, pair BMI with waist circumference (or our waist-to-height ratio), fasting glucose, lipids and blood pressure — and review with a clinician.
Asian cut-offs (overweight ≥ 23, obese ≥ 27.5)
A 2004 WHO Expert Consultation (published in The Lancet) recommended lower public-health action points for many Asian populations: overweight ≥ 23 and obese ≥ 27.5. Several Asian countries have adopted these in clinical guidelines. The Use Asian BMI thresholds checkbox on the calculator swaps in those bands.