BMI Chart: What Your BMI Score Really Means

Body Mass Index (BMI) is one of the most commonly used health screening tools. It's a simple calculation based on your height and weight that gives a rough estimate of body fat. But what do the numbers actually mean, and when should you look beyond BMI?

BMI Categories

• Under 18.5: Underweight
• 18.5 – 24.9: Normal weight
• 25.0 – 29.9: Overweight
• 30.0 and above: Obese

How BMI Is Calculated

The BMI formula is straightforward:

• Metric: BMI = weight (kg) ÷ height² (m²)
• Imperial: BMI = [weight (lbs) ÷ height² (in²)] × 703

For example, a person who is 5'10" (70 inches) and weighs 170 lbs: BMI = (170 ÷ 4900) × 703 = 24.4 — classified as normal weight.

Limitations of BMI

BMI is a useful screening tool but has well-known blind spots:

• Doesn't distinguish muscle from fat. A muscular athlete and an inactive person can have the same BMI.
• Doesn't account for fat distribution. Abdominal fat (visceral fat) is more dangerous than fat stored elsewhere.
• Varies by age and sex. Women naturally carry more body fat, and body composition changes with age.
• Not accurate for all ethnicities. Health risks at the same BMI differ across populations.

Better Used With Other Metrics

For a more complete picture, consider combining BMI with:

• Waist circumference — a waist over 40" (men) or 35" (women) signals higher risk
• Body fat percentage — measured by calipers, DEXA scan, or our body fat calculator
• Waist-to-hip ratio

Calculate your BMI instantly with our free BMI calculator.