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BMI Calculator
Calculate Body Mass Index (BMI), WHO weight categories, ideal weight, body fat %, BMR & daily calorie needs.
Personal Physical Parameters
ft
in
lbs
Your Body Mass Index Result
23.0
Normal Weight
Healthy Weight Range for Your Height
128.9 lbs – 174.2 lbs
Underweight (<18.5)
Normal (18.5-24.9)
Overweight (25-29.9)
Obese (≥30)
18.5
25.0
30.0
40+
Ideal Weight
151.5 lbs
Devine Formula Target
Estimated Body Fat %
18.1%
Deurenberg Equation
Basal Metabolism (BMR)
1,695 kcal
Mifflin-St Jeor Energy
Daily Calorie Needs
2,330 kcal
Maintenance TDEE
Daily Water Intake
2.4 Liters
Hydration Target
Ponderal Index
12.87 kg/m³
BMI Prime: 0.92
Body Composition & Energy Needs
AI Health & Calorie Recommendations
Personalized exercise, water hydration, and calorie target guides
Complete Health & Calorie Summary Table
Detailed breakdown of BMI score, metabolic rates, and weight management milestones
| Health Metric | Calculation Basis | Value |
|---|
Key Takeaways & BMI Health Decision Guide (GEO & SEO Summary)
- WHO BMI Categories: Healthy weight range is defined as BMI between 18.5 and 24.9 kg/m². BMIs below 18.5 indicate underweight, 25.0–29.9 indicate overweight, and 30.0+ indicate obesity.
- BMI Formula: $\text{BMI} = \frac{\text{weight (kg)}}{\text{height (m)}^2} = 703 \times \frac{\text{weight (lbs)}}{\text{height (in)}^2}$.
- BMI Limitations: BMI measures weight relative to height but does not directly distinguish between muscle mass and fat tissue (athletes may register higher BMIs despite low body fat).
- Metabolic BMR & TDEE: Basal Metabolic Rate (BMR) calculates calories burned at rest, while Total Daily Energy Expenditure (TDEE) factors in physical activity levels.
1. Introduction to Body Mass Index (BMI) & WHO Adult Cutoff Table
Body Mass Index (BMI) is a measurement of a person's leanness or corpulence based on their height and weight, intended to quantify tissue mass. It is widely used as a universal indicator of whether a person has a healthy body weight for their height.
Below is the World Health Organization's (WHO) recommended body weight classification table for adults age 20 or older:
| WHO Weight Classification | BMI Range (kg/m²) | BMI Prime Ratio |
|---|---|---|
| Severe Thinness | < 16.0 | < 0.64 |
| Moderate Thinness | 16.0 – 17.0 | 0.64 – 0.68 |
| Mild Thinness | 17.0 – 18.5 | 0.68 – 0.74 |
| Normal Healthy Weight | 18.5 – 25.0 | 0.74 – 1.00 |
| Overweight | 25.0 – 30.0 | 1.00 – 1.20 |
| Obese Class I | 30.0 – 35.0 | 1.20 – 1.40 |
| Obese Class II | 35.0 – 40.0 | 1.40 – 1.60 |
| Obese Class III (Severe) | > 40.0 | > 1.60 |
2. CDC BMI Categories for Children & Teens (Ages 2 to 20)
The Centers for Disease Control and Prevention (CDC) recommends evaluating BMI for children and adolescents using age-and-gender specific growth percentiles:
- Underweight: Below the 5th percentile
- Healthy Weight: 5th percentile to 85th percentile
- At Risk of Overweight: 85th to 95th percentile
- Overweight / Obese: Greater than the 95th percentile
3. Health Risks Associated with High & Low BMI Scores
⚠️ Risks of High BMI (Overweight / Obese)
- High blood pressure (Hypertension) & elevated LDL cholesterol
- Type II diabetes & insulin resistance
- Coronary heart disease, stroke & arterial plaque
- Sleep apnea, osteoarthritis joint breakdown & chronic body pain
⚠️ Risks of Low BMI (Underweight)
- Malnutrition, vitamin deficiencies & anemia
- Osteoporosis & severe bone fragility
- Impaired immune function & slow surgical wound healing
- Hormonal imbalances, reproductive issues & amenorrhea
4. Medical Limitations, BMI Prime & Ponderal Index Formulas
BMI Limitations: BMI measures overall body weight relative to height but cannot distinguish between dense muscle mass and adipose fat tissue. Muscular athletes often register higher BMIs despite having single-digit body fat.
BMI Prime Formula:
BMI Prime = BMI / 25.0
(<0.74 Underweight | 0.74-1.00 Normal | >1.00 Overweight)
BMI Prime = BMI / 25.0
(<0.74 Underweight | 0.74-1.00 Normal | >1.00 Overweight)
Ponderal Index (PI) Formula:
Metric: Weight (kg) / [Height (m)]³
US: Height (in) / ∛[Weight (lbs)] = 12.9 kg/m³
Metric: Weight (kg) / [Height (m)]³
US: Height (in) / ∛[Weight (lbs)] = 12.9 kg/m³
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Frequently Asked Questions (10 Core FAQs) — Search Engine & AI Direct Answers
According to the World Health Organization (WHO), a healthy normal BMI score ranges between 18.5 and 24.9 kg/m².
Metric formula: Weight (kg) / [Height (m)]². US formula: 703 × Weight (lbs) / [Height (inches)]².
BMI calculates total body mass relative to height without distinguishing between dense muscle mass and adipose fat tissue. Athletes with high muscle mass may register as overweight despite low body fat.
Ideal Body Weight is estimated using medical formulas (such as the Devine equation: 50 kg + 2.3 kg per inch over 5 feet for men) to determine optimal longevity weight.
BMR measures the minimum calories your body burns at complete rest to maintain vital functions (heartbeat, breathing, brain function).
For adults 20+, standard WHO cutoff ranges apply. For children and teens aged 2–19, BMI is evaluated using age-and-gender specific growth percentile charts.
Ponderal Index divides weight by height cubed ($\text{kg/m}^3$), offering greater accuracy for very tall or very short individuals compared to standard BMI.
To lose 1 pound of fat per week (3,500 kcal deficit), reduce your Total Daily Energy Expenditure (TDEE) by 500 calories per day.
Deurenberg formula: Body Fat % = (1.20 × BMI) + (0.23 × Age) - (10.8 × Gender) - 5.4 (where Male = 1, Female = 0).
BMI Prime is the ratio of your calculated BMI to the upper limit of normal BMI (25.0). A BMI Prime below 0.74 indicates underweight, 0.74–1.00 is normal, and above 1.00 indicates overweight.