Pick Normal or Advanced. The basic mode computes BMI in metric or imperial units; the advanced mode adds waist, neck and hip (women) to estimate US Navy body fat %, waist-to-height ratio and a refined healthy-weight target for your height.

Mode & units

Switch between kg/lb; we normalise everything internally.

Advanced unlocks US Navy body fat %, waist/height ratio and tailored insights.

Weight & height
kg

Physiological range: 30-250 kg.

cm

Accepted heights: 120 to 220 cm.

Target weight
18.522.027

We project the weight attached to this BMI using your height.

Result

Enter your data to see your BMI.

We validate weight and height ranges before computing anything.

--
WHO class

BMI & weight

  • Classification--
  • Ideal weight by height--
  • WHO healthy range (18.5-24.9)--
  • Age context--

Composition & risk

  • Body fat (US Navy)--
  • WHtR (waist/height)--
  • Blended insight--
Underweight Normal Overweight Obesity I Obesity II Obesity III
BMI

We place your BMI on the WHO gradient; colours adapt to light/dark mode.

Consult a professional if you are pregnant, breastfeeding or have medical conditions.

How we calculate BMI and body fat

BMI = weight in kilograms divided by height in metres squared. We convert any imperial input to SI before calculating and we check that values stay within physiological ranges to avoid invalid outputs.

Advanced mode adds the US Navy body fat equation using waist, neck and hips (women only) plus waist-to-height ratio (WHtR). Combining BMI, fat % and WHtR helps separate muscular builds from excess fat and highlights where a lower waist could improve risk.

Quick tips to read your results

  • For adults, BMI 18.5-24.9 often aligns with lower cardio-metabolic risk.
  • High BMI with low fat % and low WHtR usually signals muscle rather than fat.
  • Normal BMI but high fat % or WHtR >0.5 suggests hidden fat: review habits.
  • Under 20? Use paediatric percentiles; over 65? Interpret alongside clinical context.

FAQs

Common questions about BMI, body fat and waist measurements.

What are the WHO BMI ranges?

Under 18.5 underweight; 18.5-24.9 normal; 25-29.9 overweight; 30-34.9 obesity I; 35-39.9 obesity II; 40+ obesity III.

Why use Advanced mode?

It calculates US Navy body fat %, waist/height ratio and merges them with BMI to tell apart muscle from excess fat.

How do you estimate ideal weight?

We multiply your height squared by the WHO healthy range (18.5-24.9) and show the band plus an adjustable target BMI.

Can I enter imperial values?

Yes. Enter pounds, feet/inches or inch-based circumferences; we convert to SI before applying the formulas.

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