Calculate your BMI.

BMIHero is a free, fast, and accurate online BMI calculator designed for everyone — whether you're looking for a BMI calculator for women, a BMI calculator for men, or a child BMI calculator. Our tool supports both metric units (kg and cm) and imperial units (feet, inches, and lbs), so you get instant results regardless of where you are in the world.

What Is a BMI Calculator?

A BMI calculator uses the Body Mass Index formula to assess whether your weight is in a healthy range relative to your height. The result — your Body Mass Index score — places you into one of four standard BMI categories: underweight (below 18.5), normal weight (18.5–24.9), overweight (25–29.9), or obese (30 and above). These categories, established by the World Health Organization, are used globally as a first-line health screening metric.

BMI Calculator for Men vs. Women

While the BMI formula is identical for both sexes, the results can mean different things. Women naturally carry a higher percentage of body fat than men at the same BMI value. Our female BMI calculator and male BMI calculator both use the same proven formula — but understanding that context is key to interpreting your result correctly. A woman and a man with a BMI of 24 are both technically in the "normal weight" range, but their actual body compositions may differ significantly.

BMI by Age: Adults and Children

For adults aged 20 and older, BMI thresholds are fixed. However, for younger individuals, the interpretation is different. Our child BMI calculator follows CDC guidelines, which use age- and sex-specific growth chart percentiles rather than fixed cutoff values. If you're using a BMI calculator by age for a child or teenager (ages 2–19), the result is expressed as a percentile — a comparison to peers of the same age and gender. This approach accounts for the natural changes in body composition as children grow.

For adults over 65, some research suggests that a slightly higher BMI (around 25–27) may actually be protective against conditions like osteoporosis and sarcopenia (muscle loss). Context matters, and BMI is always best interpreted alongside other clinical measures.

Metric vs. Imperial: Calculate BMI in Any Unit

BMIHero supports BMI calculation in metric (kilograms and centimeters) and imperial (pounds, feet, and inches) formats. The metric BMI formula divides weight in kg by height in meters squared (kg/m²). The imperial version multiplies weight in pounds by 703, then divides by height in inches squared. Both produce the same BMI — just converted across unit systems. Switch between modes instantly at the top of our calculator.

Healthy Weight and BMI Chart

Understanding your healthy weight for height is one of the most practical uses of BMI. Our interactive BMI chart below shows BMI values across common heights and weights, color-coded by category. Whether you want to check a healthy BMI range for women, find the ideal weight by height, or understand where your current weight sits, the chart provides an instant visual reference.

Beyond the basic BMI score, BMIHero gives you a personalized healthy weight range — the actual weight span (in your chosen unit) that corresponds to a BMI between 18.5 and 24.9. This is actionable information: instead of just knowing your category, you know exactly where you're aiming.

Is BMI Enough?

BMI is a powerful and widely-used tool, but it has recognized limitations. It doesn't differentiate between muscle and fat, and it doesn't account for fat distribution — two critical factors in overall health. Athletes, bodybuilders, pregnant women, and very elderly individuals may find BMI less meaningful. We encourage using BMI as a starting point, paired with waist circumference, diet quality, physical activity, and regular visits to your healthcare provider.

Explore our complete guide to what BMI is, learn about healthy BMI ranges by age, gender, and ethnicity, or dive deeper into the limitations of BMI to build a full picture of your health.