BMI Calculator - Calculate Your Body Mass Index Free
Calculate your BMI (Body Mass Index) instantly with our free BMI calculator for men and women. Enter weight and height in metric (kg/cm) or imperial (lbs/in) units to get your BMI score, category, and healthy weight range using the CDC and WHO formula. Our accurate BMI calculator works 100% on your device with no signup - perfect for tracking fitness, weight loss, or checking your body mass index calculator results for adults.
Calculate Your BMI
Get your Body Mass Index and health recommendations
BMI Calculator Features
- ✓Accurate BMI calculation using standard formula
- ✓Support for both metric and imperial units
- ✓Healthy weight range recommendations
- ✓BMI category classification
- ✓Weight loss/gain recommendations
- ✓100% free BMI calculator forever
How to Calculate BMI (Formula and Instructions)
BMI (Body Mass Index) is calculated using a simple formula that compares your weight to your height. Our BMI calculator performs this calculation instantly, but understanding the formula helps you appreciate what your BMI number represents.
BMI Formula in Metric Units
BMI = weight (kg) / [height (m)]²
Example: If you weigh 70 kg and are 1.75 m tall: BMI = 70 / (1.75)² = 22.9
BMI Formula in Imperial Units
BMI = [weight (lbs) / height (in)²] × 703
Example: If you weigh 154 lbs and are 69 inches tall: BMI = (154 / 69²) × 703 = 22.7
Manual BMI Calculation Example
While you can calculate BMI manually, our online BMI calculator eliminates the need for math and provides instant, accurate results along with health recommendations.
BMI Categories and What They Mean
Underweight (BMI < 18.5)
A BMI below 18.5 indicates you may be underweight for your height. This could suggest nutritional deficiencies or other health concerns. Consider consulting a healthcare provider.
Normal Weight (BMI 18.5 - 24.9)
This is the healthy BMI range. People in this category typically have the lowest risk of weight-related health problems. Maintain your current healthy lifestyle!
Overweight (BMI 25 - 29.9)
A BMI in this range suggests you may be carrying excess weight. Consider lifestyle changes like balanced nutrition and regular exercise to reach a healthier weight range.
Obese (BMI ≥ 30)
A BMI of 30 or higher indicates obesity, which can increase risk of various health conditions. We strongly recommend consulting with a healthcare professional for personalized guidance.
Is BMI Accurate? Understanding the Limitations
While our BMI calculator provides valuable health insights, it's important to understand its limitations. BMI is a screening tool, not a diagnostic test.
BMI Limitations for Athletes
Athletes and bodybuilders with high muscle mass may have a high BMI despite low body fat. Muscle weighs more than fat, so the BMI calculator may incorrectly classify very fit individuals as overweight or obese.
BMI Limitations for Elderly
Older adults may have lower muscle mass and bone density, which can affect BMI accuracy. Additional health metrics should be considered for elderly individuals.
When to Consider Other Metrics
For a complete health picture, consider other measurements like waist circumference, body fat percentage, waist-to-hip ratio, and overall fitness level in addition to BMI.
Body Composition vs BMI
BMI doesn't distinguish between muscle and fat mass. Two people with the same BMI can have very different body compositions and health risks. Use BMI as one of several health indicators.
Healthy Weight Range for Your Height
Our BMI calculator not only calculates your current BMI but also shows you the healthy weight range for your height based on the normal BMI range (18.5-24.9).
Minimum Healthy Weight
This is the weight that corresponds to a BMI of 18.5 for your height. Going below this weight may indicate being underweight.
Maximum Healthy Weight
This is the weight that corresponds to a BMI of 24.9 for your height. Exceeding this weight moves you into the overweight category.
Ideal Weight Recommendations
While the healthy weight range is broad, many health professionals suggest aiming for the middle of the range for optimal health outcomes.
How to Use the BMI Calculator
Select Units (Metric or Imperial)
Choose between metric (kilograms and centimeters) or imperial (pounds and inches) units based on your preference.
Enter Your Weight
Input your current body weight in the selected unit (kg or lbs). Use your most recent weight for accuracy.
Enter Your Height
Input your height in the selected unit (cm or inches). Stand straight and measure accurately for best results.
View Your Results
Instantly see your BMI score, category, healthy weight range, and personalized health recommendations!
BMI for Men vs BMI for Women
The BMI calculator uses the same formula for men and women, but there are important differences to consider.
Average BMI Differences
Men typically have more muscle mass and less body fat than women at the same BMI. This means a man and woman with the same BMI may have different body fat percentages.
Healthy BMI Ranges by Gender
While the standard healthy BMI range (18.5-24.9) applies to both men and women, health risks at the same BMI can vary by gender. Some research suggests women can be healthy at slightly higher BMIs than men.
Body Fat Percentage Considerations
Women naturally have higher body fat percentages than men. A healthy body fat range is 10-20% for men and 18-28% for women, which our BMI calculator doesn't directly measure.
Frequently Asked Questions About BMI
What is a good BMI?
A good BMI is between 18.5 and 24.9, which is considered the normal weight range. This range indicates a healthy weight for your height according to the World Health Organization and CDC guidelines. Use our BMI calculator to see where you fall in this range.
Is BMI accurate for everyone?
BMI is a useful screening tool but has limitations. It may not be accurate for athletes with high muscle mass, elderly individuals, pregnant women, or growing children. Our accurate BMI calculator provides general guidelines, but for a complete health assessment, consult with a healthcare provider.
What BMI is considered healthy?
A healthy BMI falls between 18.5 and 24.9. Below 18.5 is considered underweight, 25-29.9 is overweight, and 30 or above is classified as obese. Our free BMI calculator will tell you which category you fall into.
How often should I check my BMI?
It's recommended to check your BMI every few months if you're actively managing your weight, or annually as part of routine health monitoring. Our online BMI calculator makes it easy to track changes over time.
Can BMI be misleading?
Yes, BMI does not account for muscle mass, bone density, or body composition. Athletes and very muscular individuals may have a high BMI despite being healthy. Elderly individuals may have a normal BMI but low muscle mass. It's best to use BMI calculator results as one of several health indicators.
How do I calculate BMI manually?
To calculate BMI manually, divide your weight in kilograms by your height in meters squared (BMI = kg/m²). For imperial units, divide weight in pounds by height in inches squared, then multiply by 703. However, our BMI calculator does this instantly with perfect accuracy!
What's the difference between BMI and body fat percentage?
BMI is a ratio of weight to height, while body fat percentage measures the proportion of your weight that comes from fat. Body fat percentage is more accurate but harder to measure. Our BMI calculator provides a quick screening tool, while body fat percentage requires special equipment.
Is BMI different for men and women?
The BMI calculator uses the same formula for both genders, but men and women have different body compositions at the same BMI. Women naturally have higher body fat percentages, so the same BMI may indicate different health risks for men versus women.
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