BMI Calculator

One Number That Starts a Bigger Conversation

BMI — Body Mass Index — is a simple number that puts your height and weight in relation to each other. It's not a complete picture of your health (more on that below), but it's a widely used starting point for conversations with doctors, fitness professionals, and yourself.

Knowing your BMI takes about 10 seconds with this tool. Understanding what it means takes a little more — so we'll cover both.

How BMI Is Calculated

The formula is straightforward:

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

Most people don't want to calculate this by hand. Just plug your numbers into the calculator and get your result instantly — in both metric and imperial if you prefer.

What the Numbers Mean

These categories are set by the World Health Organization and are used globally as general reference points.

The Important Caveat: BMI Has Real Limitations

BMI is a useful screening tool, but it's not a complete health assessment. Here's what it doesn't account for:

• Muscle mass: A very muscular athlete might have a "high" BMI while being in excellent health. Muscle weighs more than fat.

• Fat distribution: Where you carry fat matters as much as how much you carry. Abdominal fat carries different risks than fat stored elsewhere.

• Age and sex: BMI ranges don't fully account for the natural differences in body composition between men, women, older and younger adults.

• Ethnicity: Research suggests BMI risk thresholds may differ across ethnic groups.

Think of BMI as one data point among many, not a verdict on your health.

How to Use the Calculator

1. Enter your height (in cm or feet/inches).

2. Enter your weight (in kg or lbs).

3. Your BMI is calculated instantly, along with your category and a simple explanation.

What to Do With Your Result

• If you're in the normal range: Great starting point. Continue focusing on overall fitness, diet, and sleep.

• If you're outside the normal range: Use this as a prompt to speak with a doctor or registered dietitian. BMI alone doesn't tell the full story, but it can flag something worth exploring.

FAQ

Is BMI accurate? It's a useful rough estimate, but not a precise measure of health or body fat. Use it as one reference point, not a definitive assessment.

Should I use metric or imperial? Whichever you're more comfortable with — the results are identical. The calculator supports both.

Is BMI different for children? Yes. BMI for children and teens is calculated differently, using age- and sex-specific percentile charts. This calculator is designed for adults.

Can BMI be used for medical diagnosis? No. BMI is a screening tool, not a diagnostic one. For health decisions, always consult a qualified medical professional.