BMI Calculator

Calculate your BMI using height and weight with metric or imperial units.

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Calculate Your BMI

Your BMI:

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How To Use This BMI Calculator

  1. Select Metric or Imperial units.
  2. Enter your weight and height.
  3. Click Calculate BMI.
  4. Your BMI category will appear instantly.
Keyboard Shortcuts: Toggle between metric and imperial units with a single button click. Enter height in feet and inches separately for imperial measurements. The visual gauge immediately displays your category upon calculation. Tab between input fields using the keyboard for faster entry.

BMI Calculator Formula

BMI is calculated by dividing weight in kilograms by height in meters squared (BMI = kg / m²). In imperial units, BMI equals weight in pounds multiplied by 703, divided by height in inches squared.

Metric: BMI = weight(kg) ÷ height(m)²
Imperial: BMI = 703 × weight(lbs) ÷ height(in)²

BMI Chart for Adults

BMI Range Category
Below 18.5 Underweight
18.5 – 24.9 Normal
25 – 29.9 Overweight
30 and above Obese
Note: These categories apply to adults aged 20+ only. Children require age-specific percentile charts.

What Is BMI?

Body Mass Index (BMI) is a screening metric that divides body mass by the square of height. It categorizes individuals into underweight, normal, overweight, or obese classifications based on population health data.

Common uses: Screening for weight-related health risks during physical exams, setting fitness targets, tracking body composition changes, providing baseline data for nutritionist consultations, and evaluating athletic readiness.

Important: BMI serves as a screening tool only — it does not measure body fat percentage or overall health status directly.

BMI Limitations

BMI does not distinguish between muscle, bone, and fat mass. It can misclassify muscular people as overweight and underestimate risk in those with low muscle mass. It also doesn't account for fat distribution, frame size, pregnancy, or ethnicity-specific thresholds.

When BMI may be inaccurate: Athletes with high muscle mass, elderly adults with muscle loss, pregnant women, and certain ethnic populations (such as Asian groups who may face higher health risks at lower BMI values).

BMI for Different Groups

Women vs Men: The standard BMI formula and category thresholds are identical for adult women and men. However, women naturally carry more body fat than men at the same BMI, so clinicians often pair BMI with waist circumference or body fat percentage measurements.

Children & Teens: Standard adult categories do not apply. Pediatric BMI uses age- and sex-specific growth charts plotted as percentiles compared to other children of the same age.

BMI vs Body Fat Percentage: BMI is easy to calculate but doesn't directly measure fat. Body fat percentage (via skinfold calipers, bioelectrical impedance, or DEXA scans) more accurately reflects body composition and complements BMI for detailed assessment.