BMI Calculator (Imperial)
Calculate your Body Mass Index (BMI) using feet, inches, and pounds. Get personalized health insights and weight category classification based on your imperial measurements.
Calculate BMI (Imperial Units)
Enter your measurements to calculate your BMI:
BMI = weight (kg) ÷ [height (m)]²
Conversions: 1 lb = 0.4536 kg, 1 inch = 0.0254 m
Understanding BMI
Body Mass Index (BMI) is a simple, inexpensive, and non-invasive method for screening body fat. It uses your height and weight to estimate whether you are underweight, normal weight, overweight, or obese.
BMI Categories
| BMI Range | Category | Health Risk | Description |
|---|---|---|---|
| Below 16.5 | Severely Underweight | Very High | Severe thinness, significant health risks |
| 16.5 - 18.4 | Underweight | High | Below healthy weight range |
| 18.5 - 24.9 | Normal Weight | Low | Healthy weight range |
| 25.0 - 29.9 | Overweight | Medium | Above healthy weight range |
| 30.0 - 34.9 | Obese Class I | High | Moderately obese |
| 35.0 - 39.9 | Obese Class II | Very High | Severely obese |
| 40.0 and above | Obese Class III | Extremely High | Very severely obese |
⚕️ Important Note: BMI is a screening tool, not a diagnostic tool. It doesn't account for muscle mass, bone density, or body composition. Consult a healthcare professional for personalized health advice.
How BMI is Calculated
📐 The Formula
BMI = weight (kg) ÷ [height (m)]²
This formula was developed by Adolphe Quetelet in the 19th century
It's the same worldwide, regardless of age or gender
🔄 Imperial to Metric
Weight: pounds × 0.453592 = kilograms
Height: (feet × 12 + inches) × 0.0254 = meters
Then apply the BMI formula
📊 Interpretation
Higher BMI = higher body fat
But athletes may have high BMI due to muscle
Elderly may have lower BMI due to muscle loss
Pregnant women have naturally higher BMI
BMI Limitations
- Doesn't measure body fat directly: BMI is just a ratio of weight to height
- Ignores muscle vs. fat: Athletes and bodybuilders may have high BMI but low body fat
- Age-related changes: Older adults naturally lose muscle mass
- Pregnancy: BMI naturally increases during pregnancy
- Ethnic differences: Some ethnic groups have different body compositions
- Children and teens: Different BMI ranges apply
Health Risks by BMI Category
🟢 Normal Weight (18.5-24.9)
Lowest risk of weight-related diseases
Good energy levels
Lower risk of joint problems
Generally healthy body composition
🟡 Overweight (25-29.9)
Increased risk of type 2 diabetes
Higher blood pressure risk
Joint stress and back pain
Sleep apnea risk
🟠 Obese (30+)
Significantly higher disease risk
Heart disease and stroke
Certain cancers
Type 2 diabetes
Severe joint problems
Healthy Weight Management
🍽️ Nutrition
Balanced diet with whole foods
Portion control and mindful eating
Hydration importance
Nutrient-dense choices
🏃♂️ Exercise
150 minutes moderate activity weekly
Strength training 2-3 times/week
Find enjoyable activities
Consistency over intensity
😴 Lifestyle
7-9 hours quality sleep
Stress management
Regular health check-ups
Build healthy habits gradually
When to See a Doctor
- BMI under 16.5: Severe underweight - medical attention needed
- BMI over 35: Severe obesity - comprehensive medical evaluation
- Rapid weight changes: Unexplained weight loss or gain
- Health symptoms: Fatigue, joint pain, breathing difficulties
- Children and teens: BMI interpretation differs by age
- Pregnancy: BMI naturally changes - consult obstetrician
BMI in Different Populations
| Group | BMI Considerations | Special Notes |
|---|---|---|
| Athletes | May have high BMI due to muscle | Use body fat percentage instead |
| Elderly (65+) | Lower BMI may be healthier | Muscle loss affects BMI interpretation |
| Children (2-18) | Different percentiles apply | Use age-adjusted BMI charts |
| Pregnant Women | BMI naturally increases | Focus on healthy weight gain |
| Asian Populations | Lower BMI cutoffs for health risks | Overweight starts at BMI 23 |
| Muscle Builders | High BMI due to muscle mass | BMI not accurate for body composition |