BMI Calculator

Calculate your Body Mass Index (BMI) to evaluate if you're at a healthy weight for your height.

BMI Calculator

Your BMI Results

24.2

Normal

Body Mass Index

For your height of 5'7", a healthy weight range is:

118 - 159 lb

24.2BMI

BMI Categories

Underweight

BMI: < 18.5

Normal

BMI: 18.5 - 24.9

Overweight

BMI: 25 - 29.9

Obese Class I

BMI: 30 - 34.9

Obese Class II

BMI: 35 - 39.9

Obese Class III

BMI: ≥ 40

Health Implications

Normal Weight (BMI 18.5-24.9)

Maintaining a healthy weight reduces your risk of various health conditions. Focus on:

  • Regular physical activity (150+ minutes per week)
  • Balanced, nutritious diet
  • Regular health check-ups
  • Adequate sleep
  • Stress management

Continue your healthy lifestyle habits to maintain this weight range.

Note: BMI is a screening tool, not a diagnostic tool. It does not directly measure body fat or account for factors like muscle mass, bone density, or body composition. Always consult healthcare professionals for personalized health advice.

Understanding BMI

Body Mass Index (BMI) is a numerical value calculated from a person's weight and height. It provides a simple way to classify weight status and identify potential health risks associated with weight.

How BMI Is Calculated

BMI is calculated using the following formula:

For metric measurements:

BMI = weight (kg) / [height (m)]²

For imperial measurements:

BMI = [weight (lb) / height (in)²] × 703

BMI Categories and What They Mean

BMI values are categorized into ranges, each associated with different health implications:

  • Underweight (BMI below 18.5): May indicate malnutrition, an eating disorder, or other health problems.
  • Normal weight (BMI 18.5-24.9): Associated with the lowest health risks for most people.
  • Overweight (BMI 25-29.9): May increase the risk of health problems, particularly if accompanied by other risk factors.
  • Obesity Class I (BMI 30-34.9): Associated with a higher risk of health issues like heart disease and diabetes.
  • Obesity Class II (BMI 35-39.9): Significantly increased health risks.
  • Obesity Class III (BMI 40 or higher): Severely increases the risk of health problems and mortality.

Limitations of BMI

While BMI is a useful screening tool, it has several important limitations to keep in mind:

Muscle Mass

BMI doesn't distinguish between muscle and fat. Highly muscular individuals (like athletes) may have a high BMI despite having little body fat.

Body Composition

Two people with the same BMI can have very different body compositions and fat distributions, which affect health risks differently.

Age Considerations

BMI may be less accurate in elderly populations due to natural changes in body composition with aging, including loss of muscle mass.

Ethnic Variations

BMI thresholds may not be appropriate for all ethnic groups. For example, Asian populations may face higher health risks at lower BMI values.

Strategies for Maintaining a Healthy Weight

Whether you're looking to lose weight, gain weight, or maintain your current weight, these evidence-based strategies can help you achieve your goals:

Weight Management Approaches

For Weight Loss

  • Create a calorie deficit: Consume fewer calories than you burn
  • Focus on nutrition: Prioritize nutrient-dense foods
  • Increase physical activity: Aim for 150+ minutes of exercise weekly
  • Monitor portion sizes: Use smaller plates and read food labels
  • Stay hydrated: Drink water before meals and minimize sugary beverages

For Weight Gain

  • Create a calorie surplus: Consume more calories than you burn
  • Focus on nutrient-dense foods: Choose foods high in healthy fats and proteins
  • Eat more frequently: Have 5-6 smaller meals throughout the day
  • Incorporate strength training: Build muscle mass through resistance exercise
  • Choose calorie-rich, nutritious foods: Nuts, avocados, whole milk dairy

Evidence-Based Approaches

Research shows that certain approaches to weight management are more effective for long-term success:

Recommended Practices

  • Regular self-monitoring of weight and habits
  • Mindful eating (paying attention to hunger cues)
  • Consistent physical activity routines
  • Adequate sleep (7-9 hours nightly)
  • Social support and accountability
  • Focus on sustainable lifestyle changes

Practices to Avoid

  • Extremely restrictive diets
  • "All-or-nothing" thinking
  • Relying on supplements instead of whole foods
  • Skipping meals regularly
  • Using exercise to "earn" food
  • Ignoring emotional aspects of eating

5 Actionable Steps for Using Your BMI Results

1

Record Your Baseline Measurements

Document your current weight, BMI, and body measurements. Take photos if comfortable, as visual changes can be more motivating than numbers alone.

Action: Create a health journal or use a tracking app to monitor your metrics over time, recording measurements monthly.

2

Set SMART Goals

Create Specific, Measurable, Achievable, Relevant, and Time-bound goals for your weight and health. Focus on behavior changes rather than just weight numbers.

Example: "I will walk 30 minutes 5 days per week for the next month" rather than just "I will lose weight."

3

Develop a Balanced Eating Plan

Focus on whole foods, appropriate portion sizes, and regular meal times rather than restrictive dieting. Consider consulting a registered dietitian for personalized guidance.

Strategy: Fill half your plate with vegetables and fruits, one-quarter with lean protein, and one-quarter with whole grains.

4

Create a Sustainable Exercise Routine

Find physical activities you enjoy and can maintain long-term. Gradually increase intensity and duration, incorporating both cardiovascular exercise and strength training.

Remember: The best exercise is the one you'll actually do consistently. Start with just 10 minutes daily if you're new to exercise.

5

Seek Professional Guidance

Consider working with healthcare providers for personalized advice, especially if your BMI falls outside the healthy range or if you have underlying health conditions.

Team approach: Primary care physician for medical oversight, registered dietitian for nutrition planning, and certified personal trainer for exercise guidance.

Common BMI Calculation Mistakes to Avoid

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Relying Solely on BMI for Health Assessment

The biggest mistake is using BMI as the only indicator of health. BMI doesn't measure body fat percentage, muscle mass, or bone density. A bodybuilder with 8% body fat might have a BMI of 28 (overweight), while someone with normal BMI could have high visceral fat levels. Always consider BMI alongside other health markers like waist circumference, blood pressure, and fitness levels.

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Ignoring Ethnic and Age Differences

Standard BMI categories may not apply equally to all populations. Asian populations may face higher health risks at lower BMI values (≥23 for overweight, ≥25 for obesity), while older adults may have different optimal BMI ranges. African Americans and Pacific Islanders may also have different healthy BMI ranges due to genetic factors affecting body composition.

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Measurement Errors and Inconsistencies

Inaccurate measurements lead to incorrect BMI calculations. Common errors include weighing with clothes on, measuring height with shoes, or using different scales. For accuracy, weigh yourself naked in the morning after using the bathroom, measure height without shoes against a wall, and use the same scale consistently. A 2-pound weight error can change BMI by 0.3 units.

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Obsessing Over Daily BMI Fluctuations

Weight naturally fluctuates 2-5 pounds daily due to water retention, food intake, hormones, and other factors. Calculating BMI daily and worrying about small changes is counterproductive and can lead to unhealthy behaviors. Focus on monthly averages and long-term trends rather than daily variations. A meaningful BMI change is typically 1-2 units over several months.

BMI Considerations for Different Demographics

Age-Related Considerations

BMI interpretations should consider age-related changes in body composition:

  • Young Adults (18-25): Standard BMI categories typically apply well
  • Middle-Aged (25-65): Muscle mass begins declining; waist circumference becomes more important
  • Older Adults (65+): Slightly higher BMI (25-27) may be protective against fractures and mortality
  • Seniors (75+): Focus shifts to maintaining muscle mass and preventing sarcopenia

Gender Differences

Men and women have different body composition patterns affecting BMI interpretation:

  • Women: Naturally higher body fat percentage; hormonal changes affect weight distribution
  • Men: Higher muscle mass and bone density; tend to carry weight in abdominal area
  • Pregnancy: BMI should be calculated using pre-pregnancy weight
  • Menopause: Hormonal changes may affect optimal BMI ranges

Ethnic and Racial Considerations

Research shows that BMI thresholds may vary by ethnicity:

  • Asian Populations: Higher health risks at lower BMI values (overweight ≥23, obesity ≥25)
  • Pacific Islanders: May have higher optimal BMI ranges due to genetic factors
  • African Americans: May have lower health risks at higher BMI values
  • Hispanic/Latino: Varied optimal ranges depending on specific ancestry
  • Native Americans: Higher risk of diabetes at lower BMI values
  • Middle Eastern: May have higher health risks at lower BMI values
DR

Expert Review by Dr. Sarah Rodriguez, RD, PhD

Registered Dietitian | PhD in Nutritional Sciences | 12+ Years in Clinical Nutrition

Dr. Sarah Rodriguez is a Registered Dietitian with a PhD in Nutritional Sciences from Cornell University. She has over 12 years of experience in clinical nutrition, weight management, and metabolic health. Dr. Rodriguez has published research on body composition assessment and cultural considerations in nutrition counseling. She is a member of the Academy of Nutrition and Dietetics and the American Society for Nutrition.

"BMI is a useful screening tool, but it's essential to remember that it's just one piece of the health puzzle. I always recommend considering BMI alongside waist circumference, body fat percentage, and metabolic markers. Most importantly, focus on healthy behaviors rather than just achieving a specific BMI number."

Frequently Asked Questions

How accurate is BMI as a health indicator?

BMI is a useful screening tool but has limitations. It doesn't measure body fat directly or account for factors like muscle mass, bone density, and ethnic differences. It's most valuable as one of several health assessments rather than as a standalone diagnostic tool.

Can my BMI be "normal" but still be unhealthy?

Yes. People with a normal BMI can still have unhealthy levels of visceral fat (fat around organs), poor cardiovascular fitness, or metabolic issues. This is sometimes called "normal weight obesity" or being "skinny fat." Conversely, some individuals with an "overweight" BMI may be metabolically healthy, especially if they're physically active and have good muscle mass.

How often should I check my BMI?

For general health monitoring, checking your BMI every 3-6 months is sufficient. If you're actively trying to change your weight, you might track it monthly, but remember that healthy, sustainable weight change is gradual. Focus more on overall health improvements rather than frequent BMI calculations.

Are BMI categories the same for children and adults?

No. For children and teens, BMI is age- and sex-specific and is often referred to as "BMI-for-age." Instead of fixed categories, children's BMI is compared to percentiles for children of the same age and sex. This calculator is designed for adults aged 20 and older.

What are alternatives to BMI for assessing health?

Several other measurements can complement BMI: waist circumference, waist-to-hip ratio, body fat percentage (via skinfold measurements, bioelectrical impedance, DEXA scans), blood pressure, cholesterol levels, blood glucose levels, and cardiorespiratory fitness assessments.

Can BMI be used for athletes and very muscular people?

BMI is not ideal for athletes and highly muscular individuals because it doesn't differentiate between muscle and fat mass. A bodybuilder or NFL player might have a BMI of 28-30 (classified as overweight/obese) while having very low body fat. For these populations, body fat percentage, waist circumference, and performance metrics are more meaningful health indicators.

What BMI range is considered healthy?

For most adults, a BMI between 18.5 and 24.9 is considered healthy. However, this range may vary based on age, ethnicity, and individual factors. Asian populations may have lower healthy ranges (18.5-22.9), while older adults might have slightly higher optimal ranges (25-27). Always consider BMI alongside other health markers and consult healthcare providers for personalized guidance.

Does BMI account for age-related changes in body composition?

No, BMI doesn't account for age-related changes like muscle loss (sarcopenia) or changes in bone density. As we age, we naturally lose muscle mass and may experience changes in fat distribution. For adults over 65, slightly higher BMI values (25-27) might be protective against fractures and mortality. This is why healthcare providers often interpret BMI differently for older adults.

Can medication affect BMI or weight?

Yes, many medications can affect weight and therefore BMI. Antidepressants, antipsychotics, diabetes medications, corticosteroids, and birth control can cause weight gain. Blood pressure medications and some antidepressants might cause weight loss. If you notice significant weight changes after starting a new medication, discuss this with your healthcare provider. They may adjust dosages or suggest alternatives.

How does BMI relate to disease risk?

BMI is associated with increased risk of several diseases. Higher BMI increases risk of type 2 diabetes, heart disease, stroke, sleep apnea, certain cancers, and osteoarthritis. However, BMI alone doesn't determine disease risk - waist circumference, fitness level, family history, and other factors are equally important. Some people with higher BMI may be metabolically healthy, while others with normal BMI may have health issues.

Is it possible to have a healthy BMI but still be at risk for health problems?

Yes, this condition is sometimes called "normal weight obesity" or being "metabolically obese, normal weight." People with normal BMI can have high visceral fat, insulin resistance, poor cardiovascular fitness, or other metabolic issues. This is why waist circumference, blood markers, and fitness levels are important health indicators beyond BMI. Regular health screenings help identify these risks.

What's the difference between BMI and body fat percentage?

BMI is a ratio of weight to height that doesn't distinguish between muscle, fat, bone, and other tissues. Body fat percentage measures the proportion of fat mass to total body weight. A healthy body fat percentage is typically 10-22% for men and 20-32% for women, varying with age. Body fat percentage is more accurate for assessing health risks, especially for athletes or those with high muscle mass.

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Disclaimer: This BMI calculator is provided for informational purposes only and is not a substitute for professional medical advice. BMI has limitations and may not be suitable for all individuals, including pregnant women, athletes, and the elderly. Always consult with healthcare professionals for personalized health assessments and advice.