BMI Calculator
Calculate your Body Mass Index and assess your health risk with evidence-based recommendations for diabetes prevention and weight management.
Body Mass Index (BMI) is a measure of body fat based on height and weight that applies to adult men and women. It's calculated by dividing your weight in kilograms by your height in meters squared (kg/m²), or in imperial units, weight in pounds times 703 divided by height in inches squared.
While BMI doesn't directly measure body fat, research shows it correlates strongly with more direct measures of body fat and is a useful screening tool for weight categories that may lead to health problems.
BMI Categories:
- • Underweight: BMI < 18.5
- • Normal Weight: 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
BMI is strongly correlated with numerous health outcomes:
Type 2 Diabetes Risk
People with BMI ≥30 have 20-40x increased diabetes risk compared to normal weight. Each 1-unit increase in BMI is associated with 12% higher diabetes risk.
Cardiovascular Disease
Overweight and obesity significantly increase risk of heart disease, stroke, and hypertension. BMI ≥25 is associated with elevated cardiovascular mortality.
Cancer Risk
Higher BMI is linked to increased risk of several cancers including breast, colon, endometrial, kidney, and pancreatic cancer.
All-Cause Mortality
Both very low BMI (<18.5) and high BMI (≥30) are associated with increased mortality risk. Optimal BMI for longevity is typically 20-25.
If your BMI indicates overweight or obesity, even modest weight loss produces significant health benefits:
7-10% Weight Loss Benefits:
- • 58% reduction in diabetes risk (Diabetes Prevention Program)
- • 5-10 mmHg reduction in blood pressure
- • 15% reduction in LDL cholesterol
- • 30% reduction in triglycerides
- • Improved insulin sensitivity and glycemic control
- • Reduced inflammation markers
- • Better cardiovascular function
Recommended Approach:
The most effective approach combines:
- • Mediterranean diet (proven longevity benefits)
- • 150+ minutes/week moderate-intensity exercise
- • Resistance training 2-3x weekly (preserves muscle mass)
- • Behavioral modifications and stress management
- • Adequate sleep (7-9 hours nightly)
While BMI is a useful screening tool, it has important limitations:
- Doesn't distinguish muscle from fat: Athletes and muscular individuals may have high BMI despite low body fat
- Doesn't measure fat distribution: Visceral (abdominal) fat is more dangerous than subcutaneous fat
- Age and sex variations: Older adults and women typically have higher body fat at same BMI
- Ethnic differences: Asian populations have higher health risks at lower BMI thresholds
Better Alternatives for Body Composition:
- • Waist circumference (≥40" men, ≥35" women indicates increased risk)
- • Waist-to-hip ratio
- • Body fat percentage (see our Body Fat Calculator)
- • DEXA scan (gold standard for body composition)
Asian American Populations
Diabetes and cardiovascular risk increases at BMI >23 (vs >25 for general population). The American Diabetes Association recommends diabetes screening for Asian Americans at BMI ≥23 with additional risk factors.
Older Adults (65+)
Slightly higher BMI (25-27) may be protective in older adults. Focus on maintaining muscle mass and functional capacity rather than achieving lowest BMI.
Athletes and Highly Active Individuals
BMI may overestimate body fat in individuals with high muscle mass. Consider body composition measurements like body fat percentage or DEXA scan for more accurate assessment.
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Medical Disclaimer
This BMI calculator is for educational and informational purposes only. BMI is a screening tool and does not diagnose body fatness or health. Consult with qualified healthcare providers for personalized medical advice, diagnosis, and treatment plans. Individual health needs vary, and BMI should be considered alongside other health metrics and risk factors.