BMI (Body Mass Index) is a number calculated from your height and weight. It is a widely used screening tool to identify weight categories — underweight, normal weight, overweight and obese — that may indicate potential health risks.

What is a healthy BMI range for adults?

According to WHO guidelines, a BMI between 18.5 and 24.9 is considered normal weight. Under 18.5 is underweight; 25–29.9 is overweight; 30 or above is obese. BMI thresholds can differ for some Asian populations.

How is BMI calculated?

BMI is calculated as weight in kilograms divided by height in metres squared (kg/m²). In imperial units: (weight in pounds × 703) ÷ (height in inches)². The GoChronos BMI calculator handles both metric and imperial conversions automatically.

Is BMI the same for men and women?

The BMI formula is identical for both sexes, but body fat percentage at the same BMI typically differs. Women naturally carry more body fat. Athletes may show a high BMI due to muscle mass rather than excess fat.

Is the GoChronos BMI calculator free?

Yes. GoChronos BMI Calculator is completely free, ad-free and works without an account. All calculations run in your browser — no data is uploaded or stored.

BMI Calculator — Body Mass Index & WHO Weight Categories

Calculate your body mass index in metric or imperial units, with WHO weight categories and an ideal-weight range. Free, private, nothing uploaded.