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Body Mass Index (BMI)

Enter your weight and height to calculate your Body Mass Index (BMI). You can switch between metric (kg/cm) and US units (lbs/in).

kg
cm

BMI Categories

BMI is categorized into different weight classes based on the calculated value. These categories help assess health risks associated with body weight.

Underweight < 18.5
Normal 18.5 - 24.9
Overweight 25.0 - 29.9
Obese Class I 30.0 - 34.9
Obese Class II 35.0 - 39.9
Obese Class III ≥ 40.0

BMI is a single number from height and weight. Clinicians use it as a coarse screen; athletes and pregnant people often sit outside the usual bands. Treat the category as context, not a verdict.

What this tool does

It divides weight in kilograms by height in metres squared (with automatic conversion from pounds and inches), then maps the result to widely cited underweight/normal/overweight/obese ranges.

How to use it

  1. Choose metric or US units.
  2. Enter height and weight.
  3. Read the index and category note.

What you get

  • Toggle units without leaving the page.
  • Immediate recalculation on input change.
  • Plain-language category labels.

Typical uses

  • Tracking a general trend between check-ups.
  • Understanding what a doctor’s chart refers to.
  • Classroom demos of how BMI is computed.

Examples

  • 70 kg, 175 cm → BMI ≈ 22.9 (commonly “normal” band)
  • Unit swap shows equivalent BMI

Worth knowing

  • Muscle mass can push BMI high without excess fat.
  • Children and teens use different charts—this targets typical adult screening.

Frequently asked

Is BMI medical advice?

No. It is an educational screening number; consult professionals for health decisions.

Why two unit systems?

Readers arrive from different regions; both are first-class here.

A fast BMI readout—pair it with professional guidance when it matters.