BMI Calculator

BMI Calculator FAQ

What is BMI and how is it calculated?

BMI (Body Mass Index) is a simple screening metric calculated by dividing your weight in kilograms by your height in meters squared (kg/m²). It provides a rough estimate of body fatness based on height and weight alone.

Is BMI accurate for athletes and muscular people?

BMI does not distinguish between muscle and fat mass. Athletes, bodybuilders, and people with above-average muscle mass often show an 'overweight' BMI despite being healthy and lean. In these cases, body fat percentage or waist circumference are better indicators.

What is a healthy BMI range?

The WHO classifies a BMI between 18.5 and 24.9 as 'normal weight.' Below 18.5 is considered underweight, 25-29.9 is overweight, and 30+ is classified as obese. However, these ranges are population-level guidelines — individual health depends on many factors beyond BMI.

How often should I check my BMI?

For general health monitoring, checking BMI once a month is sufficient. If you are actively losing or gaining weight, weekly checks can help track trends. Remember that daily fluctuations in water weight are normal and do not reflect real changes in body composition.

Does BMI differ by age or gender?

The standard BMI formula does not adjust for age or gender, though body composition changes with both. Older adults naturally lose muscle mass, meaning the same BMI may represent more body fat. Some health organizations use adjusted thresholds for elderly populations.