BMI Calculator

Calculate Body Mass Index & Health Status. Free BMI calculator to assess health weight ranges using metric or imperial measurements.

What is BMI and Why Does It Matter?

Body Mass Index (BMI) is a widely-used health screening tool that measures the relationship between weight and height. Calculated as weight (kg) divided by height (m) squared, BMI provides a quick assessment of whether someone is at a healthy weight range for their height. While BMI isn't perfect and doesn't measure body composition directly, it's an important first-line health indicator used by doctors, fitness professionals, and health organizations worldwide to identify potential health risks.

Understanding BMI Categories

Underweight (BMI < 18.5): Below healthy weight range. May indicate insufficient nutrition or underlying health issues. Associated with bone density loss, weakened immunity, and fertility problems.

Normal Weight (BMI 18.5-24.9): Healthy weight range with lowest disease risk. This is the target range for most people. Maintaining this range supports cardiovascular health, joint function, and overall wellness.

Overweight (BMI 25-29.9): Above healthy weight range. Increases risk for type 2 diabetes, heart disease, and high blood pressure. Weight loss of even 5-10% can significantly improve health markers.

Obese Class I (BMI 30-34.9): Significant health risks. Associated with diabetes, hypertension, sleep apnea, and joint stress. Medical intervention often recommended.

Obese Class II (BMI 35-39.9): High health risks requiring professional guidance. Substantially increases cardiovascular disease, stroke, and mortality risk.

Obese Class III (BMI ≥ 40): Very high health risk requiring medical attention. Significantly increases risk of multiple serious health conditions.

How BMI is Calculated

The BMI formula is simple: BMI = weight (kg) / height (m)². In imperial units: BMI = [weight (lbs) / height (inches)²] × 703. Our calculator handles both metric (kilograms/centimeters) and imperial (pounds/inches) systems, automatically converting to standard units. This allows anyone worldwide to assess their health status using familiar measurements.

Limitations of BMI

While useful, BMI has important limitations. It doesn't distinguish between muscle and fat—a bodybuilder might have a high BMI from muscle, not fat. Age, gender, and ethnicity can affect healthy BMI ranges. Athletes and very muscular individuals may be classified as overweight despite excellent health. Conversely, sedentary people with normal BMI might lack muscle. BMI should be one health indicator among many, including fitness level, blood pressure, cholesterol, and overall lifestyle.

Healthy Weight Range for Your Height

Our calculator displays your healthy weight range—the pounds or kilograms where your BMI would fall between 18.5-24.9. For someone 5'10", the healthy range is roughly 132-179 lbs. Knowing this range helps set realistic weight goals. Rather than aiming for an arbitrary number, targeting your healthy range ensures sustainable health improvement aligned with medical guidelines.

Using BMI for Health and Fitness Goals

BMI can guide health improvement efforts. If you're overweight, a realistic goal might be reducing BMI by 1-2 points annually through combined diet and exercise changes. Even reaching the upper end of normal weight (BMI 24.9) provides significant health benefits if starting from obese categories. For fitness tracking, calculate BMI monthly alongside other metrics like body composition, energy levels, and clothing fit. BMI is one data point in a comprehensive health picture.

Tips for Using BMI Effectively

  • Track trends, not single measurements: BMI fluctuates daily with water weight and meals. Monitor monthly averages for meaningful trends
  • Consider your build: Large-framed individuals may naturally have slightly higher BMI. Discuss with healthcare provider
  • Account for muscle: Athletes and very fit individuals shouldn't obsess over BMI numbers. Assess overall health holistically
  • Combine with other metrics: Use BMI alongside waist circumference, fitness level, and blood work for complete picture
  • Set realistic goals: Even 5-10% weight loss from overweight ranges provides substantial health improvements
  • Consult healthcare providers: Before starting weight loss programs, discuss goals and methods with doctors

BMI Calculator Tool

Your Measurements

Your Results

Your BMI
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Category
Normal Weight
Healthy Weight Range
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Ideal Weight (Mid-range)
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BMI Categories
  • Underweight: BMI < 18.5
  • Normal: 18.5 - 24.9
  • Overweight: 25 - 29.9
  • Obese: BMI ≥ 30
BMI Scale

Frequently Asked Questions About BMI

No, BMI can overestimate body fat in very muscular individuals since it doesn't distinguish muscle from fat. Athletes may have high BMI despite low body fat. For athletic individuals, body composition analysis (DEXA scan, body fat percentage) provides better assessment than BMI alone.
Standard BMI categories apply universally, but some populations have different health risk associations. For children, BMI is age and gender-adjusted (BMI percentiles). Some ethnic groups may have different disease risks at the same BMI. Always discuss your individual BMI with healthcare providers considering your unique health profile.
Research shows just 5-10% weight loss from your current weight provides significant health benefits: lower blood pressure, improved cholesterol, reduced diabetes risk, better joint health, and improved sleep quality. You don't need to reach ideal BMI immediately—gradual progress yields lasting results.
BMI measures weight relative to height. Body composition measures muscle, fat, and bone percentages specifically. Two people with identical BMI can have very different body compositions. Body composition analysis (via DEXA, bioelectrical impedance, or calipers) provides more detail but is less convenient than BMI calculation.
The "ideal" BMI depends on individual factors: body type, age, genetics, and fitness level. For most people, anywhere in the 18.5-24.9 range is healthy. Some naturally larger-framed individuals may be healthiest at the higher end (around 24.5). Discuss your ideal BMI target with your healthcare provider based on your individual health profile.
Monthly BMI checks are reasonable for tracking weight loss progress. More frequent checks (weekly) can be discouraging due to daily weight fluctuations from water, meals, and hormones. If maintaining weight, checking quarterly or annually is sufficient. Use BMI as one of several health metrics rather than obsessing over exact numbers.