BMI Calculator

Body Mass Index (BMI) is a simple screening tool that uses your height and weight to flag whether you may be underweight, at a healthy weight, overweight, or obese. It was developed in the 19th century by Belgian statistician Adolphe Quetelet and was originally intended for studying populations, not diagnosing individuals.

Today, doctors and insurance companies use BMI as a quick first-pass health indicator because it's easy to compute and correlates reasonably well with body-fat-related health risks at a population level. But it's a blunt tool — read the "When to use this" and "Common mistakes" sections below before drawing conclusions from your number.

Someone who is 175 cm (5'9") tall and weighs 70 kg (154 lb):

• Height in meters: 175 ÷ 100 = 1.75
• BMI = 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 ≈ 22.9
• That falls in the healthy-weight range (18.5–24.9).

For the imperial version: 154 × 703 ÷ (69 × 69) = 108,262 ÷ 4,761 ≈ 22.7. The small difference is rounding.

• Annual health check-ins — a quick number to track over time alongside other measurements.
• Initial screening — useful for flagging when a deeper conversation with a doctor is worthwhile.
• Weight-loss or weight-gain tracking — combined with how your clothes fit and how you feel.
• Insurance and clinical settings — many providers still use BMI cutoffs for risk classification.

• Treating BMI as a diagnosis. It's a screening number, not a verdict on your health.
• Ignoring muscle mass. Athletes and weightlifters routinely score "overweight" despite low body fat.
• Applying it to children with adult cutoffs. Kids need percentile-based BMI charts.
• Forgetting fat distribution. Visceral fat around the abdomen is more dangerous than fat in the hips/thighs — BMI doesn't see this.
• Comparing across ethnicities without adjustment. Some populations (e.g. South Asian) face elevated cardiovascular risk at lower BMIs than the standard cutoffs suggest.