BMI Calculator
Calculate BMI from height (cm) and weight (kg). Example: 70 kg, 175 cm → 22.9 (Normal). WHO categories. Not medical advice.
Calculate your Body Mass Index (BMI) from weight (kg) and height (cm). Results show your BMI and WHO category (Underweight, Normal, Overweight, Obese). This tool is for informational use only and is not medical advice. See the disclaimer below.
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Examples
- 70 kg, 175 cm → BMI 22.9 (Normal)
- 60 kg, 165 cm → BMI 22.0 (Normal)
FAQ
How is BMI calculated?
BMI = weight (kg) / height (m)². Enter height in cm. The calculator converts to meters (÷ 100) and uses the same formula.
What are WHO BMI categories?
Underweight < 18.5, Normal 18.5–24.9, Overweight 25–29.9, Obese 30+.
Why cm only for height?
This calculator uses metric only: weight in kg and height in cm for simplicity.
Is BMI accurate for everyone?
BMI is a simple screening tool and does not account for muscle mass, bone density, or body composition. It is not a diagnosis. Consult a healthcare provider for health decisions.
How do I calculate BMI in Imperial units (lbs and inches)?
BMI = (weight in lbs × 703) / (height in inches)². Example: 154 lbs, 5 ft 8 in (68 inches): BMI = (154 × 703) / (68²) = 108,262 / 4624 ≈ 23.4. Alternatively convert: 154 lbs ÷ 2.205 = 69.8 kg, 68 in × 2.54 = 172.7 cm, then use this tool.
Why is BMI inaccurate for muscular people?
Muscle is denser than fat. A muscular athlete may have a high BMI but very low body fat. BMI cannot distinguish between fat mass and lean mass. A bodybuilder with 10% body fat may register as 'Overweight' or 'Obese'.
How does BMI differ for children vs adults?
For adults, BMI is interpreted against fixed thresholds (18.5–24.9 = Normal). For children (2–19 years), BMI is compared against age and sex-specific growth charts (BMI-for-age percentiles). A child's BMI of 22 might be healthy or overweight depending on age.
What are better alternatives to BMI?
Waist-to-hip ratio (WHR) measures abdominal fat. Waist circumference alone is a strong predictor of metabolic risk. Body fat percentage (DEXA scan, skinfolds, bioelectrical impedance) is more accurate. Waist-to-height ratio is also a simple and effective metric.
What BMI is considered healthy for different populations?
The standard WHO thresholds (18.5–24.9) were derived from Western populations. Some studies suggest lower cutoffs for Asian populations (23.0 for overweight, 27.5 for obese) because metabolic risk increases at lower BMI levels in people of Asian descent.
Does BMI affect health insurance in the US?
Some US employer wellness programs offer premium discounts for employees within a target BMI range. The ACA prohibits health insurers from using BMI alone to deny coverage, but BMI may affect life insurance premiums and coverage.
Is a BMI of 25 overweight or normal?
BMI of exactly 25.0 is the boundary — WHO classifies 25.0–29.9 as 'Overweight'. A BMI of 24.9 is 'Normal'. The boundary is a threshold in a continuous scale; small differences near 25 have little practical health significance.
How does age affect ideal BMI?
Research suggests that slightly higher BMI (around 25–27) may be associated with better outcomes in older adults (65+), possibly because fat reserves protect against illness and injury. The 'obesity paradox' is a topic of active research.