Examples
BMI — Worked Examples
5 real worked examples for the BMI calculator. See how we solve common scenarios with full step-by-step math.
Adult with normal BMI
Scenario
A 30-year-old woman, 165 cm tall, 60 kg.
Inputs
- Height
- 165 cm (1.65 m)
- Weight
- 60 kg
Calculation steps
- BMI = weight / height²
The standard formula.
- BMI = 60 / (1.65)²
Plug in the values.
- BMI = 60 / 2.7225
Square the height.
- BMI = 22.04
Final result.
Result
BMI = 22.04 → Normal weight (18.5–24.9)
Overweight adult
Scenario
A 45-year-old man, 178 cm tall, 95 kg.
Inputs
- Height
- 178 cm (1.78 m)
- Weight
- 95 kg
Calculation steps
- BMI = 95 / (1.78)²
- BMI = 95 / 3.1684
- BMI = 29.98
Result
BMI = 29.98 → Overweight (25–29.9), borderline obese
Underweight teen (use percentile for <20)
Scenario
A 16-year-old girl, 162 cm tall, 42 kg. Note: teens need age/sex percentiles.
Inputs
- Height
- 162 cm (1.62 m)
- Weight
- 42 kg
- Age
- 16
- Sex
- Female
Calculation steps
- BMI = 42 / (1.62)²
- BMI = 42 / 2.6244
- BMI = 16.00
- BMI-for-age percentile: 5th percentile (underweight)
CDC chart lookup.
Result
BMI = 16.00 → 5th percentile (Underweight)
Athlete with high BMI but low body fat
Scenario
A 28-year-old male bodybuilder, 180 cm tall, 95 kg, with 12% body fat.
Inputs
- Height
- 180 cm (1.80 m)
- Weight
- 95 kg
- Body fat
- 12%
Calculation steps
- BMI = 95 / (1.80)²
- BMI = 95 / 3.24
- BMI = 29.32
- Lean mass: 95 × (1 − 0.12) = 83.6 kg
Calculating fat-free mass.
- Body fat % suggests this is high muscle, not obesity.
BMI is misleading for athletes.
Result
BMI = 29.32 (overweight category), but body composition shows athletic build. Use body fat % or DEXA scan for accurate assessment.
Older adult with healthy BMI but muscle loss
Scenario
A 72-year-old woman, 162 cm tall, 58 kg. Same BMI as the 30-year-old above.
Inputs
- Height
- 162 cm (1.62 m)
- Weight
- 58 kg
- Age
- 72
Calculation steps
- BMI = 58 / (1.62)²
- BMI = 58 / 2.6244
- BMI = 22.10
- Sarcopenia risk: same BMI, but muscle mass typically 20-30% lower than at 30.
Aging reduces lean mass.
Result
BMI = 22.10 (normal), but with age-related muscle loss, body fat % may be 30%+. Combine BMI with waist circumference for better insight.